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Bài 2: Phương trình lượng giác cơ bản

Giải phương trình sau: cos3x = cos12o

Toán Lớp 11
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Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 10)

Mark the letter A, B, C or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions

Tiếng Anh Tốt nghiệp THPT
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18 Bài tập phản ứng tráng bạc của monosaccarit

Đun nóng 40,5 gam dung dịch glucozơ với lượng AgNO3 trong môi trường NH3 dư, thu được 9,72 gam bạc. Nồng độ % của dung dịch glucozơ là

Hóa học Lớp 12
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Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherLook at the verb accelerate in paragraph 3. Which of the following is the closest in meaning to _____.

Tiếng Anh Tốt nghiệp THPT
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Đề ôn luyện thi THPTQG Sinh Học có lời giải (Đề số 17)

Về mặt sinh thái, sự phân bố các cá thể cùng loài một cách đồng đều trong môi trường có ý nghĩa: 

Sinh học Tốt nghiệp THPT
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Bài 2: Phương trình lượng giác cơ bản

Giải phương trình sau: cos(x - 1) = 2/3

Toán Lớp 11
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Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 10)

Mark the letter A, B, C or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions

Tiếng Anh Tốt nghiệp THPT
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18 Bài tập phản ứng tráng bạc của monosaccarit

Đun nóng dung dịch chứa 21,60 gam glucozơ với dung dịch AgNO3 trong NH3 (dư), khối lượng Ag thu được là

Hóa học Lớp 12
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Ôn tập chương 4 (Câu hỏi - Bài tập)

Giải phương trình bằng cách đặt ẩn phụ:x+1x2-4.x+1x+3=0

Toán Lớp 9
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Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherAccording to the passage, people respond to loud noises in the same way that they respond to ___.

Tiếng Anh Tốt nghiệp THPT
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Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the question below.We find that bright children are rarely held back by mixed-ability teaching. On the contrary, both their knowledge and experience are enriched. We feel that there are many disadvantages in streaming pupils. It does not take into account the fact that children develop at different rates. It can have a bad effect on both the bright and the not-so-bright child. After all, it can be quite discouraging to be at the bottom of the top grade!Besides, it is rather unreal to grade people just according to their intellectual ability. This is only one aspect of their total personality. We are concerned to develop the abilities of all our pupils to the full, not just their academic ability. We also value personal qualities and social skills, and we find that mixed-ability teaching contributes to all these aspects of learning.In our classroom, we work in various ways. The pupils often work in groups; this gives them the opportunity to learn to co-operate, to share, and to develop leadership skills. They also learn how to cope with the personal problems as well as learning how to think, to make decisions, to analyze and evaluate, to communicate effectively. The pupils learn from each other as well as from the teachers.Sometimes the pupils work in pairs; sometimes the work on individual tasks and assignments, they can do this at their own speed. They also have some formal class teaching when this is appropriate. We encourage our pupils to use the library, and we teach them the skills they need in order to do this effectively. An advanced pupil can do advanced works; it does not matter what age the child is. We expect our pupils to do their best, not their least, and we give them every encouragement to attain this goalThe author argues that a teacher’s chief concern should be the development of the pupils’ _________

Tiếng Anh Tốt nghiệp THPT
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Tổng hợp đề ôn tập thi THPTQG môn Sinh Học có đáp án (Đề số 16)

Hô hấp không có vai trò nào sau đây?I. Cung cấp năng lượng cho toàn bộ hoạt động cơ thểII. Cung cấp oxi cho cơ thể và thải CO2 ra môi trường ngoài.III. Mang oxi từ cơ quan hô hấp đến cho tế bào và mang CO2 từ tế bào về cơ quan hô hấp.IV. Cung cấp các sản phẩm trung gian cho quá trình đồng hóa các chất.Số phương án đúng là

Sinh học Tốt nghiệp THPT
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BÀI TẬP TÍNH TOÁN

Thực hiện phản ứng nhiệt nhôm hỗn hợp gồm Al và Cr2O3 trong điều kiện không có không khí. Sau một thời gian thu được 21,95 gam hỗn hợp X. Chia X thành hai phần bằng nhau. Cho phần 1 vào lượng dư dung dịch HCl loãng nóng, thu được 3,36 lít H2 (đktc). Hòa tan phần 2 vào lượng dư dung dịch NaOH đặc nóng, thu được 1,68 lít H, (đktc). Biết các phản ứng của phần 1 và phần 2 đều xảy ra hoàn toàn. Hiệu suất phản ứng nhiệt nhôm là

Hóa học Lớp 12
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Bài 2: Phương trình lượng giác cơ bản

Với những giá trị nào của x thì giá trị của các hàm số y = sin 3x và y = sin x bằng nhau?

Toán Lớp 11
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Bài 2: Phương trình lượng giác cơ bản

Giải phương trình sau: sin2x + 20° = -32

Toán Lớp 11
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Bài kiểm tra Lipit - Chất béo có lời giải chi tiết (Đề số 2)

Cho các cặp chất phenol và (CH3CO)2O; triolein và H2; axetilen và CH3COOH; axit axetic và C2H5OH; axit axetic và CH3CHO. Số cặp chất khi phản ứng tạo ra este (điều kiện phản ứng cho đủ) là

Hóa học Lớp 12
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Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the question below.We find that bright children are rarely held back by mixed-ability teaching. On the contrary, both their knowledge and experience are enriched. We feel that there are many disadvantages in streaming pupils. It does not take into account the fact that children develop at different rates. It can have a bad effect on both the bright and the not-so-bright child. After all, it can be quite discouraging to be at the bottom of the top grade!Besides, it is rather unreal to grade people just according to their intellectual ability. This is only one aspect of their total personality. We are concerned to develop the abilities of all our pupils to the full, not just their academic ability. We also value personal qualities and social skills, and we find that mixed-ability teaching contributes to all these aspects of learning.In our classroom, we work in various ways. The pupils often work in groups; this gives them the opportunity to learn to co-operate, to share, and to develop leadership skills. They also learn how to cope with the personal problems as well as learning how to think, to make decisions, to analyze and evaluate, to communicate effectively. The pupils learn from each other as well as from the teachers.Sometimes the pupils work in pairs; sometimes the work on individual tasks and assignments, they can do this at their own speed. They also have some formal class teaching when this is appropriate. We encourage our pupils to use the library, and we teach them the skills they need in order to do this effectively. An advanced pupil can do advanced works; it does not matter what age the child is. We expect our pupils to do their best, not their least, and we give them every encouragement to attain this goalThe phrase “held back” in paragraph 1 means ______

Tiếng Anh Tốt nghiệp THPT
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BÀI TẬP VỀ PHẢN ỨNG ESTE HÓA

Cho hỗn hợp X gồm ancol etylic và hỗn hợp 2 axit no, đơn chức kế tiếp nhau trong dãy đồng đẳng, tác dụng hết với Na giải phóng ra 4,48 lít H2 ( đktc). Mặt khác, nếu đun nóng hỗn hợp X (xt: H2SO4 đặc) thì các chất trong hỗn hợp X phản ứng vừa đủ với nhau tạo thành 16,2g hỗn hợp este. CTCT thu gọn của 2 axit là:

Hóa học Lớp 12
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Tổng hợp đề thi thử môn Tiếng Anh có lời giải chi tiết (Đề số 1)

Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50. (1) The protozoans, minute, aquatic creatures each of which consists of a single cell of protoplasm, constitute a classification of the most primitive forms of animal life. They are fantastically diverse, but three major groups may be identified on the basis of their motility. The Mastigophora have one or more long tails, which they use to project themselves forward. The Ciliata, which use the same basic means for locomotion as the Mastigophora, have a larger number of short tails. The Sarcodina, which include amoebae, float or row themselves about on their crusted bodies. (2) In addition to their form of movement, several other features discriminate among the three groups of protozoans. For example, at least two nuclei per cell have been identified in the Ciliata, usually a large nucleus that regulates growth but decomposes during reproduction, and a smaller one that contains the genetic code necessary to generate the large nucleus. (3) Protozoans are considered animals because, unlike pigmented plants to which some protozoans are otherwise almost identical, they do not live on simple organic compounds. Their cell demonstrates all of the major characteristics of the cells of higher animals. (4) Many species of protozoans collect into colonies, physically connected to each other and responding uniformly to outside stimulate. Current research into this phenomenon, along with investigations carried out with advanced microscopes may necessitate a redefinition of what constitutes protozoans, even calling into question the basic premise that they have only one cell. Nevertheless, with the current data available, almost 40,000 species of protozoans have been identified. No doubt, as the technology improves our methods of observation, better models of classification will be proposed. Which of the following statements are NOT true of protozoans?

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 397 lượt xem 6 năm trước
18 Bài tập phản ứng tráng bạc của monosaccarit

Cho 13,00 gam glucozơ tác dụng với lượng dư dung dịch AgNO3 trong NH3, đun nóng (hiệu suất phản ứng tráng bạc đạt 80%), khối lượng kết tủa bạc (gam) thu được là

Hóa học Lớp 12
Xem chi tiết 790 lượt xem 6 năm trước
Bài kiểm tra Lipit - Chất béo có lời giải chi tiết (Đề số 2)

Cho glixerol phản ứng với hỗn hợp gồm C17H35COOH, C17H33COOH, C17H31COOH và C15H31COOH; số loại chất béo (chứa đồng thời 3 gốc axit khác nhau) tối đa có thể tạo thành là

Hóa học Lớp 12
Xem chi tiết 1.2 K lượt xem 6 năm trước
Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the question below.We find that bright children are rarely held back by mixed-ability teaching. On the contrary, both their knowledge and experience are enriched. We feel that there are many disadvantages in streaming pupils. It does not take into account the fact that children develop at different rates. It can have a bad effect on both the bright and the not-so-bright child. After all, it can be quite discouraging to be at the bottom of the top grade!Besides, it is rather unreal to grade people just according to their intellectual ability. This is only one aspect of their total personality. We are concerned to develop the abilities of all our pupils to the full, not just their academic ability. We also value personal qualities and social skills, and we find that mixed-ability teaching contributes to all these aspects of learning.In our classroom, we work in various ways. The pupils often work in groups; this gives them the opportunity to learn to co-operate, to share, and to develop leadership skills. They also learn how to cope with the personal problems as well as learning how to think, to make decisions, to analyze and evaluate, to communicate effectively. The pupils learn from each other as well as from the teachers.Sometimes the pupils work in pairs; sometimes the work on individual tasks and assignments, they can do this at their own speed. They also have some formal class teaching when this is appropriate. We encourage our pupils to use the library, and we teach them the skills they need in order to do this effectively. An advanced pupil can do advanced works; it does not matter what age the child is. We expect our pupils to do their best, not their least, and we give them every encouragement to attain this goalIn the passage, the author’s attitude towards “mixed-ability teaching” is ________

Tiếng Anh Tốt nghiệp THPT
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Ôn tập chương 4 (Câu hỏi - Bài tập)

Giải phương trình bằng cách đặt ẩn phụ:2x2-2x2+3x2-2x+1=0

Toán Lớp 9
Xem chi tiết 7.3 K lượt xem 1 năm trước
18 Bài tập phản ứng tráng bạc của monosaccarit

Cho 0,9 gam glucozơ (C6H12O6) tác dụng hết với lượng dư dung dịch AgNO3 trong NH3, thu được m gam Ag. Giá trị của m là

Hóa học Lớp 12
Xem chi tiết 1.1 K lượt xem 6 năm trước
Bài 2: Phương trình lượng giác cơ bản

Giải phương trình sau: sin2x3-π3 = 0

Toán Lớp 11
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Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherThe word it in the first paragraph refers to ___.

Tiếng Anh Tốt nghiệp THPT
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Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 9)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct  answer to each of the following questions                                The ability to conduct electricity is one of the key properties of  a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved  in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost  electrons. This leaves the metal atoms with a positive charge and they are now strictly  ions. The lost electrons are free to move in what are known  as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.            An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow. Freshwater Aquarium FishPlaylist Freshwater Aquarium Fish       Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.By Helena Gillespie and Rob Gillespie. Science for Primary School Teacher. OUPWhich of the following could best serve as the title of the passage?

Tiếng Anh Tốt nghiệp THPT
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Đề ôn luyện thi THPTQG Sinh Học có lời giải (Đề số 17)

Điều nào sau đây đầy đủ nhất về cấu tạo của cơ thể sinh vật? 

Sinh học Tốt nghiệp THPT
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BÀI TẬP VỀ PHẢN ỨNG ESTE HÓA

Thực hiện phản ứng este hóa giữa axit axetic và hỗn hợp gồm 8,4 gam 3 ancol là đồng đẳng của ancol etylic. Sau phản ứng thu được 16,8 gam 3 este. Lấy sản phẩm của phản ứng este hóa trên thực hiện phản ứng xà phòng hóa với dung dịch NaOH 4M thì thu được m gam muối: (Giả sử hiệu suất phản ứng este hóa là 100%). Giá trị của m là

Hóa học Lớp 12
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Tổng hợp đề ôn tập thi THPTQG môn Sinh Học có đáp án (Đề số 16)

Hô hấp hiếu khí và lên men giống nhau ở điểm nào sau đây?I. Đều sử dụng nguyên liệu là chất hữu cơ.II. Đều cần cung cấp oxi.III. Sản phẩm cuối cùng đều là axit piruvic.IV. Đều tạo ra năng lượng ATP.V. Đều cần H2O và giải phóng CO2.VI. Đều sử dụng hệ enzim photphorin hóa, oxi hóa.Số phương án đúng là

Sinh học Tốt nghiệp THPT
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Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherThe word congested in paragraph 1 could best be replaced by _

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 382 lượt xem 6 năm trước
Bài kiểm tra Lipit - Chất béo có lời giải chi tiết (Đề số 2)

Este X là sản phẩm este hóa giữa glixerol với hỗn hợp 2 axit béo no stearic và panmitic. Biết X tác dụng được với kim loại Na giải phóng khi H2. Số hợp chất thỏa mãn tính chất của X là

Hóa học Lớp 12
Xem chi tiết 3.1 K lượt xem 6 năm trước
Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 9)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct  answer to each of the following questions                                The ability to conduct electricity is one of the key properties of  a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved  in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost  electrons. This leaves the metal atoms with a positive charge and they are now strictly  ions. The lost electrons are free to move in what are known  as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.            An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow. Freshwater Aquarium FishPlaylist Freshwater Aquarium Fish       Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.By Helena Gillespie and Rob Gillespie. Science for Primary School Teacher. OUPWhich of the following is NOT true according to the passage?

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 688 lượt xem 6 năm trước
Tổng hợp đề thi thử môn Tiếng Anh có lời giải chi tiết (Đề số 1)

Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50. (1) The protozoans, minute, aquatic creatures each of which consists of a single cell of protoplasm, constitute a classification of the most primitive forms of animal life. They are fantastically diverse, but three major groups may be identified on the basis of their motility. The Mastigophora have one or more long tails, which they use to project themselves forward. The Ciliata, which use the same basic means for locomotion as the Mastigophora, have a larger number of short tails. The Sarcodina, which include amoebae, float or row themselves about on their crusted bodies. (2) In addition to their form of movement, several other features discriminate among the three groups of protozoans. For example, at least two nuclei per cell have been identified in the Ciliata, usually a large nucleus that regulates growth but decomposes during reproduction, and a smaller one that contains the genetic code necessary to generate the large nucleus. (3) Protozoans are considered animals because, unlike pigmented plants to which some protozoans are otherwise almost identical, they do not live on simple organic compounds. Their cell demonstrates all of the major characteristics of the cells of higher animals. (4) Many species of protozoans collect into colonies, physically connected to each other and responding uniformly to outside stimulate. Current research into this phenomenon, along with investigations carried out with advanced microscopes may necessitate a redefinition of what constitutes protozoans, even calling into question the basic premise that they have only one cell. Nevertheless, with the current data available, almost 40,000 species of protozoans have been identified. No doubt, as the technology improves our methods of observation, better models of classification will be proposed. The word “they” in paragraph 3 refers to

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 565 lượt xem 6 năm trước
Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction in each of the following questions.I think she will be suitable for the work because she has been working like a teacher for a long time.

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 1.4 K lượt xem 6 năm trước
Đề ôn luyện thi THPTQG Sinh Học có lời giải (Đề số 17)

Dạng đột biến cấu trúc nhiễm sắc thể không làm ảnh hưởng đến số lượng vật chất di truyền là

Sinh học Tốt nghiệp THPT
Xem chi tiết 282 lượt xem 6 năm trước
Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 9)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct  answer to each of the following questions                                The ability to conduct electricity is one of the key properties of  a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved  in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost  electrons. This leaves the metal atoms with a positive charge and they are now strictly  ions. The lost electrons are free to move in what are known  as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.            An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow. Freshwater Aquarium FishPlaylist Freshwater Aquarium Fish       Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.By Helena Gillespie and Rob Gillespie. Science for Primary School Teacher. OUPWe can have problems when touching electrical devices with wet hands because               .

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 655 lượt xem 6 năm trước
Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherWhy is noise difficult to measure?

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 2.8 K lượt xem 6 năm trước
BÀI TẬP TÍNH TOÁN

Tiến hành phản ứng nhiệt nhôm hỗn hợp X gồm 0,03 mol Cr2O3; 0,04 mol FeO và a mol Al. Sau một thời gian phản ứng, trộn đều, thu được hỗn hợp chất rắn Y. Chia Y thành hai phần bằng nhau. Phần một phản ứng vừa đủ với 400 ml dung dịch NaOH 0,lM (loãng). Phần hai phản ứng với dung dịch HCl loãng, nóng (dư), thu được 1,12 lít khí (đktc). Giả sử trong phản ứng nhiệt nhôm, Cr2O3 chỉ bị khử thành Cr. Phần trăm khối lượng Cr2O3 đã phản ứng là

Hóa học Lớp 12
Xem chi tiết 329 lượt xem 6 năm trước
Bài kiểm tra Lipit - Chất béo có lời giải chi tiết (Đề số 2)

Chất nào sau đây tác dụng với tripanmitin

Hóa học Lớp 12
Xem chi tiết 12.5 K lượt xem 6 năm trước
Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction in each of the following questions.The old woman cannot remember the place which she kept her savings

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 14.5 K lượt xem 6 năm trước
Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherAccording to the passage, what is noise?

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 402 lượt xem 6 năm trước
BÀI TẬP VỀ PHẢN ỨNG ESTE HÓA

Oxi hóa anđehit OHCCH2CH2CHO trong điều kiện thích hợp thu được hợp chất hữu cơ X. Đun nóng hỗn hợp gồm 1 mol X và 1 mol ancol metylic với xúc tác H2SO4 đặc thu được 2 este Z và Q( MZ < MQ) với tỉ lệ khối lượng mZ:mQ=1,81. Biết chỉ có 72% ancol chuyển thành este. Số mol Z và Q lần lượt là: 

Hóa học Lớp 12
Xem chi tiết 692 lượt xem 6 năm trước
Bài kiểm tra Lipit - Chất béo có lời giải chi tiết (Đề số 2)

Chất khi đun nóng với dung dịch NaOH (dư), không sinh ra ancol là:

Hóa học Lớp 12
Xem chi tiết 529 lượt xem 6 năm trước
Tổng hợp đề thi thử môn Tiếng Anh có lời giải chi tiết (Đề số 1)

Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50. (1) The protozoans, minute, aquatic creatures each of which consists of a single cell of protoplasm, constitute a classification of the most primitive forms of animal life. They are fantastically diverse, but three major groups may be identified on the basis of their motility. The Mastigophora have one or more long tails, which they use to project themselves forward. The Ciliata, which use the same basic means for locomotion as the Mastigophora, have a larger number of short tails. The Sarcodina, which include amoebae, float or row themselves about on their crusted bodies. (2) In addition to their form of movement, several other features discriminate among the three groups of protozoans. For example, at least two nuclei per cell have been identified in the Ciliata, usually a large nucleus that regulates growth but decomposes during reproduction, and a smaller one that contains the genetic code necessary to generate the large nucleus. (3) Protozoans are considered animals because, unlike pigmented plants to which some protozoans are otherwise almost identical, they do not live on simple organic compounds. Their cell demonstrates all of the major characteristics of the cells of higher animals. (4) Many species of protozoans collect into colonies, physically connected to each other and responding uniformly to outside stimulate. Current research into this phenomenon, along with investigations carried out with advanced microscopes may necessitate a redefinition of what constitutes protozoans, even calling into question the basic premise that they have only one cell. Nevertheless, with the current data available, almost 40,000 species of protozoans have been identified. No doubt, as the technology improves our methods of observation, better models of classification will be proposed. The word “uniformly” in paragraph 4 is closest in meaning to

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 405 lượt xem 6 năm trước
Đề luyện thi THPT quốc gia môn tiếng anh có lời giải (Đề số 10)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased. Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each otherWhich of the following is the author’s main point?

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 316 lượt xem 6 năm trước
Kỳ thi thử thpt quốc gia lần 1 năm 2019 môn Tiếng Anh cực hay có lời giải(Đề 9)

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct  answer to each of the following questions                                The ability to conduct electricity is one of the key properties of  a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved  in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost  electrons. This leaves the metal atoms with a positive charge and they are now strictly  ions. The lost electrons are free to move in what are known  as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.            An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow. Freshwater Aquarium FishPlaylist Freshwater Aquarium Fish       Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.By Helena Gillespie and Rob Gillespie. Science for Primary School Teacher. OUPWater is a poor conductor because it contains                    

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 789 lượt xem 6 năm trước
Ôn tập chương 4 (Câu hỏi - Bài tập)

Giải các phương trình: 5x3 – x2 – 5x + 1 = 0

Toán Lớp 9
Xem chi tiết 6.5 K lượt xem 1 năm trước
Tổng hợp đề ôn tập thi THPTQG môn Sinh Học có đáp án (Đề số 16)

Cho lưới thức ăn đồng cỏ đơn giản như hình bên. Hãy cho biết trong các nhận xét sau, có bao nhiêu nhận xét đúng?(1) Lưới thức ăn này chỉ có một loại chuỗi thức ăn.(2) Diều hâu có thể là sinh vật tiêu thụ bậc 3 hoặc sinh vật tiêu thụ bậc 4.(3) Ếch và chuột cùng thuộc một bậc dinh dưỡng.(4) Rắn là sinh vật thuộc bậc dinh dưỡng cấp 4 và là một mắc xích chung.(5) Chuột và ếch có sự trùng lặp ổ sinh thái.

Sinh học Tốt nghiệp THPT
Xem chi tiết 11.1 K lượt xem 6 năm trước
Tổng hợp đề thi Tiếng Anh có lời giải (Đề số 14)

Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction in each of the following questions.The abilities to work hard, follow directions, and thinking independently are some of the  criteria for success in the workplace

Tiếng Anh Tốt nghiệp THPT
Xem chi tiết 616 lượt xem 6 năm trước

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