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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       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.The use of the phrase “come in handy” indicates that the process is ______

Xem chi tiết 1.1 K lượt xem 4 năm trước

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       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.It can be inferred from the passage, in the early spring, the buds of plants __________.

Xem chi tiết 1.7 K lượt xem 4 năm trước

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       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.What is the main topic of the passage?

Xem chi tiết 1.6 K lượt xem 4 năm trước

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       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.Which of the following best describes the organization of the passage?

Xem chi tiết 723 lượt xem 4 năm trước

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 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! According to the passage, which of the following NOT true about the tradition of tooth giving in the West? 

Xem chi tiết 566 lượt xem 4 năm trước

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 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! The word "origins" in paragraph 2 is closest in meaning to ________.

Xem chi tiết 690 lượt xem 4 năm trước

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 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! According to paragraph 2, parents in Mongolia feed their child's lost tooth to a dog because ________. 

Xem chi tiết 633 lượt xem 4 năm trước

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 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! The word “their” in paragraph 1 refers to ________. 

Xem chi tiết 2.1 K lượt xem 4 năm trước

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 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! What is the passage mainly about? 

Xem chi tiết 1.5 K lượt xem 4 năm trước

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 1 to 7.      Birds that feed in flocks commonly retire together into roosts. The reasons for roosting communally are not always obvious, but there are some likely benefits. In winter especially, it is important for birds to keep warm at night and conserve precious food reserves. One way to do this is to find a sheltered roost. Solitary roosters shelter in dense vegetation or enter a cavity – horned larks dig holes in the ground and ptarmigan burrow into snow banks - but the effect of sheltering is magnified by several birds huddling together in the roosts, as wrens, swifts, brown creepers, bluebirds, and anis do. Body contact reduces the surface area exposed to the cold air, so the birds keep each other warm. Two kinglets huddling together were found to reduce their heat losses by a quarter, and three together saved a third of their heat.      The second possible benefit of communal roosts is that they act as “information centers”. During the day, parties of birds will have spread out to forage over a very large area. When they return in the evening some will have fed well, but others may have found little to eat. Some investigators have observed that when the birds set out again next morning, those birds that did not feed well on the previous day appear to follow those that did. The behavior of common and lesser kestrels may illustrate different feeding behaviors of similar birds with different roosting habits. The common kestrel hunts vertebrate animals in a small, familiar hunting ground, whereas the very similar lesser kestrel feeds on insects over a large area. The common kestrel roosts and hunts alone, but the lesser kestrel roosts and hunts in flocks, possibly so one bird can learn from others where to find insect swarms.           Finally, there is safety in numbers at communal roosts since there will always be a few birds awake at any given moment to give the alarm. But this increased protection is partially counteracted by the fact that mass roosts attract predators and are especially vulnerable if they are on the ground. Even those in trees can be attacked by birds of prey. The birds on the edge are at greatest risk since predators find it easier to catch small birds perching at the margins of the roostThe word “they” refers to ________. 

Xem chi tiết 866 lượt xem 4 năm trước