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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 from 43 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?

A. It and nitrogen always exist in equal amounts in any substance

B. Its half-life is more than 5,000 years

C. It can decay into nitrogen-14

D. It is radioactive

1
23 tháng 10 2018

Đáp án A

Câu nào dưới đây KHÔNG ĐÚNG về carbon-14? 

A. Nó và nitơ luôn tồn tại với số lượng bằng nhau trong bất kỳ chất nào. 

B. Thời gian bán hủy của nó là hơn 5.000 năm. 

C. Nó có thể phân rã thành nitơ-14. 

D. Nó là chất phóng xạ. 

Các đáp án B, C, D có thông tin được tìm thấy trong bài. 

B + C- Dẫn chứng ở câu đầu đoạn 2: “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”- (Carbon-14 có thời gian bán hủy là 5,570 năm, có nghĩa là sau từng ấy năm, một nửa các nguyên tử carbon-14 đã bị phân hủy thành nitơ-14). 

D- Dẫn chứng ở câu cuối đoạn 1: “Since a radioactive substance such as carbon-14 has a known half-life, […]” – (Bởi vì một chất phóng xạ thí dụ như carbon-14 có thời gian bán hủy như đã biết, […]) => Carbon-14 là một chất phóng xạ. 

=> Còn lại đáp án A không đúng.

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 43 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...
Đọc tiếp

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 43 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 miniscule 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 _______.

A. not as much as 5,570 years old

B. too old to be age-dated with carbon-14

C. too radioactive to be used by archeologists

D. more than 5.570 years old

1
31 tháng 1 2018

Đáp án A.

Có thể suy ra từ đoạn văn rằng nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì vật đó_____                     

A. không đến 5.570 năm tuổi

B. quá lâu đời đ có thế xác định được niên đại với carbon-14

C. chứa quá nhiều phóng xạ để được sử dụng bởi các nhà khảo cổ.

D. trên 5.570 năm tui.

Dựa vào đoạn 2: “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-lá, this indicates that around half of the carbon- 14 has decayed into nitrogen-14, and the sample is approximately 5.570 years old”: Carbon-14 có thời gian bán hủy 5,570 năm, nghĩa là sau từng ấy năm, một nửa các nguyên tử carbon-14 đã bị phân hủy thành nitơ-14. Chính tỷ lệ carbon-14 có trong chất đó cho thấy độ tuổi của nó. Thí dụ như, nếu trong một mẫu vật cụ thể lượng cacbon-14 tương đương với lượng nitơ- 14, điều đó chỉ ra rằng khoảng một nửa lượng carbon- 14 đã phân hủy thành nitơ-14, và mẫu vật đó có niên đại khoảng 5,570 tui.

Nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì chứng tỏ nó chưa hoàn tất chu kì bán hủy của mình kéo dài trong 5.570 năm nên vật đó chưa tới 5.570 tuổi.

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 43 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...
Đọc tiếp

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 43 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______.

A. not as much as 5,570 years old

B. too old to be age-dated with carbon-14

C. too radioactive to be used by archeologists

D. more than 5.570 years old

1
25 tháng 2 2017

Đáp án A

Có thể suy ra từ đoạn văn rằng nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì vật đó ______.

A. không đến 5.570 năm tuổi

B. quá lâu đời để có thể xác định được niên đại với carbon-14. 

C. chứa quá nhiều phóng xạ để được sử dụng bởi các nhà khảo cổ. 

D. trên 5.570 năm tuổi. 

Dựa vào đoạn 2: “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-14 có thời gian bán hủy là 5,570 năm, có nghĩa là sau từng ấy năm, một nửa các nguyên tử carbon-14 đã bị phân hủy thành nitơ-14. Chính tỷ lệ carbon-14 có trong chất đó cho thấy độ tuổi của nó. Thí dụ như, nếu trong một mẫu vật cụ thể lượng cacbon-14 tương đương với lượng nitơ-14, điều đó chỉ ra rằng khoảng một nửa lượng carbon-14 đã phân hủy thành nitơ-14, và mẫu vật đó có niên đại khoảng 5,570 tuổi.). 

=>Nếu nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì chứng tỏ nó chưa hoàn tất chu kì bán hủy của mình kéo dài trong 5.570 năm => vật đó chưa tới 5.570 tuổi.

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...
Đọc tiếp

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______.

A. not as much as 5,570 years old

B. too old to be age-dated with carbon-14

C. too radioactive to be used by archeologists 

D. more than 5.570 years old

1
4 tháng 1 2019

Đáp án A

Có thể suy ra từ đoạn văn rằng nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì vật đó ______.

A. không đến 5.570 năm tuổi

B. quá lâu đời để có thể xác định được niên đại với carbon-14.

C. chứa quá nhiều phóng xạ để được sử dụng bởi các nhà khảo cổ.

D. trên 5.570 năm tuổi.

Dựa vào đoạn 2: “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-14 có thời gian bán hủy là 5,570 năm, có nghĩa là sau từng ấy năm, một nửa các nguyên tử carbon-14 đã bị phân hủy thành nitơ-14. Chính tỷ lệ carbon-14 có trong chất đó cho thấy độ tuổi của nó. Thí dụ như, nếu trong một mẫu vật cụ thể lượng cacbon-14 tương đương với lượng nitơ-14, điều đó chỉ ra rằng khoảng một nửa lượng carbon-14 đã phân hủy thành nitơ-14, và mẫu vật đó có niên đại khoảng 5,570 tuổi.). =>Nếu nếu một vật có chứa nhiều các-bon 14 hơn ni-tơ 14, thì chứng tỏ nó chưa hoàn tất chu kì bán hủy của mình kéo dài trong 5.570 năm => vật đó chưa tới 5.570 tuổi.

Dịch bài

 Phương pháp xác định niên đại bằng carbon có thể được sử dụng để ước lượng tuổi của bất kì chất hữu cơ tự nhiên nào, nó được sử dụng thành công trong lĩnh vực khảo cổ học để xác định tuổi của các cổ vật, hóa thạch cổ cũng như là trong nhiều lĩnh vực khác. Nguyên tắc làm cơ sở tiền đề cho việc sử dụng phương pháp xác định niên đại bằng carbon đó là carbon là một phần của tất cả các sinh vật sống trên trái đất. Bởi vì một chất phóng xạ thí dụ như carbon-14 có thời gian bán hủy như đã biết, lượng carbon-14 còn lại trên một vật có thể được sử dụng để xác định tuổi của vật đó.

Carbon-14 có thời gian bán hủy là 5,570 năm, có nghĩa là sau từng ấy năm, một nửa các nguyên tử carbon-14 đã bị phân hủy thành nitơ-14. Chính tỷ lệ carbon-14 có trong chất đó cho thấy độ tuổi của nó. Thí dụ như, nếu trong một mẫu vật cụ thể lượng cacbon-14 tương đương với lượng nitơ-14, điều đó chỉ ra rằng khoảng một nửa lượng carbon-14 đã phân hủy thành nitơ-14, và mẫu vật đó có niên đại khoảng 5,570 tuổi.

Phương pháp xác định niên đại bằng carbon không thể được sử dụng có hiệu quả đối với cổ vật trên 80,000 tuổi. Đối với những cổ vật có tuổi đời như vậy, phần lớn carbon-14 đã hoàn toàn phân hủy thành nitơ-14, và lượng phân tử còn lại không đáng tin cậy để đo lường được độ tuổi. Trong trường hợp đối với những cổ vật có niên đại lâu hơn, những phương pháp xác định niên đại khác mới có khả dụng, những phương pháp sử dụng các nguyên tử phóng xạ có thời gian bán hủy lâu hơn carbon.

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 43 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...
Đọc tiếp

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 43 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 miniscule 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?

A. It and nitrogen always exist in equal amounts in any substance.

B. Its half-life is more than 5,000 years.

C. It can decay into nitrogen-14.

D. It is radioactive.

1
29 tháng 4 2019

Đáp án A.

Câu nào dưới đây KHÔNG ĐÚNG về carbon-14?

A. Nó và nitơ luôn tn tại với số lượng bằng nhau trong bất kỳ chất nào.

B. Thời gian bán hủy của nó là hơn 5.000 năm.

C. Nó có th phân rã thành nitơ-14.

D. Nó là chất phóng xạ.

Các đáp án B, C, D có thông tin được tìm thấy trong bài. B + C- Dn chứng ở câu đầu đoạn 2: “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”: Carbon-14 có thời gian bán hủy 5.570 năm, có nghĩa là sau từng ẩy năm, một nửa các nguyên từ carbon-14 đã bị phân hủy thành nitơ-14. D- Dn chứng ở câu cuối đoạn 1 : “Since a radioactive substance such as carbon-14 has a known half-life, [...]”: Bởi vì một chất phóng xạ thí dụ như carbon-14 có thời gian bán hủy như đã biết, [...])Carbon-14 là một chất phóng xạ.

Còn lại đáp án A không đúng.

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 43 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...
Đọc tiếp

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 43 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 miniscule 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 .

A. carbon dating has no known uses outside of archeology

B. fossils cannot be age-dated using carbon-14

C. carbon dating could not be used on an item containing nitrogen

D. carbon-14 does not have the longest known half-life

1
26 tháng 1 2018

Đáp án D.

Đoạn văn ngụ ý rằng_________                   

A. phương pháp xác định niên đại bằng các-bon không được biết đến ngoài ngành khảo c học.

B. hóa thạch không thể xác định được niên đại bằng cách sử dụng carbon-14.

C. phương pháp xác định niên đại bằng cácbon không th sử dụng trên vật có chứa ni-tơ.

D. carbon-14 không có chu kỳ bán rã dài nhất được biết đến.

Từ Question 48 ta suy ra vẫn còn có chất khác có chu kì bán rã dài hơn carbon-14 đxác định được niên đại của những c vật trên 80,000 tui.

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 43 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...
Đọc tiếp

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 43 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 miniscule 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________.

A. precisely

B. harshly

C. approximately

D. coarsely

1
21 tháng 8 2018

Đáp án C.

- rougth (adv) C. approximately (adv): xấp xỉ, khoảng chừng.

Các đáp án còn lại:

A. precisely (adv): chính xác.

B. harshly (adv): khắc nghiệt.

D. coarsely (adv): thô, không đúng cách.

Tạm dịch: “If, for example, in a particular sample the amount of carbon-14 is mugth equivalent to the amount of nitrogen-M14, [...]”: Thí dụ như nếu trong một mu vật cụ th lượng cacbon-14 tương đương với lượng nitơ- 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 43 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...
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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 from 43 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______.

A. precisely

B. Harshly

C. approximately

D. coarsely

1
20 tháng 1 2018

Đáp án C

Câu hỏi từ vựng. 

Roughly (adv) = C. approximately (adv): xấp xỉ, khoảng chừng. 

Các đáp án còn lại: 

A. precisely (adv): chính xác. 

B. harshly (adv): khắc nghiệt. 

D. coarsely (adv): thô, không đúng cách. 

Tạm dịch: “If, for example, in a particular sample the amount of carbon-14 is roughly equivalent to the amount of nitrogen-14, […]”- (Thí dụ như, nếu trong một mẫu vật cụ thể lượng cacbon-14 tương đương với lượng nitơ-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 43 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...
Đọc tiếp

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 43 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 miniscule 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” in paragraph I could best be replaced by _______.

A. below

B. requiring

C. serving as a basis for

D. being studied through

1
25 tháng 8 2018

Đáp án C.

- underlying (adj): cơ bản, cơ sở = C. serving as a basis for: làm cơ sở cho.

Các đáp án còn lại:

A. bên dưới.

B. yêu cầu.

D. đang được nghiên cứu qua.

Tạm dịch: “The principle underlying the use of carbon dating is that carbon is a part of all living things on Earth": Nguyên tắc làm cơ sở tiền đề cho việc sử dụng phương pháp xác định niên đại bằng carbon đó là carbon là một phần của tất cả các sinh vật sống trên trái đất.

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 43 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...
Đọc tiếp

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 43 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______.

A. carbon dating has no known uses outside of archeology

B. fossils cannot be age-dated using carbon-14

C. carbon dating could not be used on an item containing nitrogen

D. carbon-14 does not have the longest known half-life

1
6 tháng 11 2019

Đáp án D

Đoạn văn ngụ ý rằng______.

A. phương pháp xác định niên đại bằng các-bon không được biết đến ngoài nghành khảo cổ học. 

B. hóa thạch không thể xác định được niên đại bằng cách sử dụng carbon-14. 

C. phương pháp xác định niên đại bằng các-bon không thể sử dụng trên vật có chứa ni-tơ. 

D. carbon-14 không có chu kỳ bán rã dài nhất được biết đến. 

Từ câu 48 ta suy ra vẫn còn có chất khác có chu kì bán rã dài hơn carbon-14 để xác định được niên đại của những cổ vật trên 80,000 tuổi.