20 Đề ôn thi Tiếng Anh chuẩn cấu trúc có lời giải chi tiết (Đề số 15)

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.

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.

Mark the letter A, B, C, or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

Drying food by means of solar energy is an ancient process applying wherever climatic conditions make it possible

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

More and 90 percent of the calcium in the human body is in the skeleton.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

Regardless of your teaching method, the objective of any conversation class should be for the students to practice speaking words

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

I regret going to the cinema. I wish I ______. 

He may be quick ______ understanding but he isn't capable ______ remembering anything

Vitamin D is necessary to aid the ______ of calcium from food

The ______ were told to fasten their seat belts as the plane began its descent.

I get quite depressed when I think about the damage we are ______ to the environment

Unfortunately, we’ve made ______. 

______, Mozart was an accomplished compose while still a child

______ parents of Thomas claimed that he was at ______ the time of ______ robbery

Like most marine mammals and land mammals, whales are ______ creatures

We insist that more money ______ in education

Certainly, man must ______ the future, and find ways of providing for his need.

After I ______ from college, I ______ as a teacher

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges

John: “You’re already leaving? The ball is only starting.”

Mary: “But it is very late, so ______.” 

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.

Daisy: “______?”

Mary: “No, that’s about it for now.”

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.

Such problems as haste and inexperience are a universal feature of youth.

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.

I stayed there with her for a while before I left

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions.

I am glad that we see eye to eye on the matter of the conference location.

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions.

I don’t want to live in this filthy colony

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions

Apart from being conveniently located near the beach, that hotel has nothing about it to make me recommend it to you.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions. 

Although she was very old, she looked very grateful

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

 “Why don’t you ask your parents for advice?” said Tom

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions

Farmers depend on meteorologists. They need meteorologists’ accurate forecasts for successful agricultural planning

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions

Sports clear my mind. They also help me maintain a healthy lifestyle

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word for each of the blanks from 1 to 5.

Swim, Cycle, and Run

    For athletes who like to (31)______a variety of endurance sports in a single race, triathlons are a great fit. These competitions (32) ______running, cycling, and swimming into one race, and they take place one after the other in a single continuous timed race. Athletes who participate must be in top physical form and have the skills needed to complete each portion of the race.
    Training for triathlons means the athletes have to become proficient not only in the sport required in each stage, but they also have to become familiar with what (33) ______from one to the other does to their bodies. Many inexperienced triathletes are surprised to (34) ______hard it can be to switch from swimming to cycling to running, and how tired their muscles can suddenly feel. One thing all triathletes can agree (35) ______is that no one ever told them that running a triathlon would be easy

Điền ô số 31

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word for each of the blanks from 1 to 5.

Swim, Cycle, and Run

    For athletes who like to (31)______a variety of endurance sports in a single race, triathlons are a great fit. These competitions (32) ______running, cycling, and swimming into one race, and they take place one after the other in a single continuous timed race. Athletes who participate must be in top physical form and have the skills needed to complete each portion of the race.
    Training for triathlons means the athletes have to become proficient not only in the sport required in each stage, but they also have to become familiar with what (33) ______from one to the other does to their bodies. Many inexperienced triathletes are surprised to (34) ______hard it can be to switch from swimming to cycling to running, and how tired their muscles can suddenly feel. One thing all triathletes can agree (35) ______is that no one ever told them that running a triathlon would be easy

Điền ô số 32

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word for each of the blanks from 1 to 5.

Swim, Cycle, and Run

    For athletes who like to (31)______a variety of endurance sports in a single race, triathlons are a great fit. These competitions (32) ______running, cycling, and swimming into one race, and they take place one after the other in a single continuous timed race. Athletes who participate must be in top physical form and have the skills needed to complete each portion of the race.
    Training for triathlons means the athletes have to become proficient not only in the sport required in each stage, but they also have to become familiar with what (33) ______from one to the other does to their bodies. Many inexperienced triathletes are surprised to (34) ______hard it can be to switch from swimming to cycling to running, and how tired their muscles can suddenly feel. One thing all triathletes can agree (35) ______is that no one ever told them that running a triathlon would be easy

Điền ô số 33

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word for each of the blanks from 1 to 5.

Swim, Cycle, and Run

    For athletes who like to (31)______a variety of endurance sports in a single race, triathlons are a great fit. These competitions (32) ______running, cycling, and swimming into one race, and they take place one after the other in a single continuous timed race. Athletes who participate must be in top physical form and have the skills needed to complete each portion of the race.
    Training for triathlons means the athletes have to become proficient not only in the sport required in each stage, but they also have to become familiar with what (33) ______from one to the other does to their bodies. Many inexperienced triathletes are surprised to (34) ______hard it can be to switch from swimming to cycling to running, and how tired their muscles can suddenly feel. One thing all triathletes can agree (35) ______is that no one ever told them that running a triathlon would be easy

Điền ô số 34

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word for each of the blanks from 1 to 5.

Swim, Cycle, and Run

    For athletes who like to (31)______a variety of endurance sports in a single race, triathlons are a great fit. These competitions (32) ______running, cycling, and swimming into one race, and they take place one after the other in a single continuous timed race. Athletes who participate must be in top physical form and have the skills needed to complete each portion of the race.
    Training for triathlons means the athletes have to become proficient not only in the sport required in each stage, but they also have to become familiar with what (33) ______from one to the other does to their bodies. Many inexperienced triathletes are surprised to (34) ______hard it can be to switch from swimming to cycling to running, and how tired their muscles can suddenly feel. One thing all triathletes can agree (35) ______is that no one ever told them that running a triathlon would be easy

Điền ô số 35

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

What is implied in the last sentence of the passage? 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

In order to achieve our goals, we should______. 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

Which of the following statements does the author support most? 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

The word “this” in paragraph 3 refers to______. 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

The phrase “hacks for” in the title is closest in meaning to______. 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

Which of the following sentences is true? 

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 36 to 42.

Productivity Hacks for Great Success

 No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.

 If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.

 In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.

 Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”

What is the Pareto principle?

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

This passage is mainly about______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

Which of the following is NOT true about carbon-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 questions from 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

The word “it” in paragraph 1 refers to______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

The word “underlying” could best be replaced by______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

The word “roughly” in paragraph 2 is closest in meaning to______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

The paragraph following the passage most probably discusses______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

It is implied in the passage that______. 

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 13 to 50.

          Carbon dating can be used to estimate the age of any organic natural material; it has been used successfully in archeology to determine the age of ancient artifacts or fossils as well as in a variety of other fields. The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth. Since a radioactive substance such as carbon-14 has a known half-life, the amount of carbon-14 remaining in an object can be used to date that object.
          Carbon-14 has a half-life of 5,570 years, which means that after that number of years, half of the carbon- 14 atoms have decayed into nitrogen-14. It is the ratio of carbon-14 in that substance that indicates the age of the substance. If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, this indicates that around half of the carbon-14 has decayed into nitrogen-14, and the sample is approximately 5,570 years old.
          Carbon dating cannot be used effectively in dating objects that are older than 80,000 years. When objects are that old, much of the carbon-14 has already decayed into nitrogen-14, and the molecule amount that is left doesn’t provide a reliable measurement of age. In the case of older objects, other age-dating methods are available, methods which use radioactive atoms with longer half-lives than carbon has

It can be inferred from the passage that if an item contains more carbon-14 than nitrogen-14, then the item is______.