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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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

The creation of helium within stars ______ 

A. produces hydrogen as a by-product 

B. causes helium to be much more abundant in old stars than in young st

C. produces energy 

D. cannot be measured 

1
23 tháng 1 2017

Kiến thức: Đọc hiểu

Giải thích:

Việc tạo ra helium trong các ngôi sao ______

   A. sản xuất hydro dưới dạng sản phẩm phụ B. làm cho helium có nhiều ở các ngôi sao tồn tại đã lâu hơn nhiều so với sao mới được hình thành

   C. tạo ra năng lượng   D. không thể đo được

Thông tin: Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce.

Tạm dịch: Helium được tạo ra trong các ngôi sao. Trong thực tế, phản ứng hạt nhân mà chuyển đổi Hydro thành Heli đảm nhiệm hầu hết năng lượng mà các ngôi sao tạo ra.

Chọn C 

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

Why does the author mention "cosmic rays"?

A. To explain the abundance of hydrogen in the universe 

B. To explain how the universe began 

C. As an example of an unsolved astronomical puzzle 

D. As part of a list of things containing helium 

1
20 tháng 1 2019

Kiến thức: Đọc hiểu

Giải thích:

Tại sao tác giả đề cập đến “các tia vũ trụ”?

   A. Để giải thích sự phong phú của hydro trong vũ trụ                     B. Để giải thích về việc vũ trụ bắt đầu như thế nào

   C. Để lấy ví dụ về câu đố về thiên văn chưa giải quyết                     D. Nó là một phần của danh sách những thứ có chứa khí heli

Thông tin: Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth

Tạm dịch: Hạt nhân helium cũng đã được tìm thấy là thành phần của các tia vũ trụ chiếu xuống Trái đất

Chọn D

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

The word "constituents" is closest in meaning to _____ 

A. causes 

B. components 

C. relatives 

D. targets 

1
27 tháng 8 2019

Kiến thức: Đọc hiểu, từ vựng

Giải thích:

constituent (n): thành phần

cause (n): nguyên nhân component (n): thành phần

relative (n): họ hàng target (n): mục tiêu

=> constituent = component

Thông tin: Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth

Tạm dịch: Hạt nhân helium cũng đã được tìm thấy là thành phần của các tia vũ trụ chiếu xuống Trái đất

Chọn B

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

The word "vary" is closest in meaning to 

A. include 

B. mean 

C. stretch 

D. change 

1
1 tháng 9 2017

Kiến thức: Đọc hiểu, từ vựng

Giải thích:

vary (v): thay đổi

include (v): bao gồm                                        mean (v): có nghĩa là

stretch (v): căng ra                                           change (v): thay đổi

=> vary = change

Thông tin: Its relative abundance never seems to vary much.

Tạm dịch: Sự phong phú tương đối của nó dường như không bao giờ thay đổi nhiều.

Chọn D

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

According to the passage, helium is ________ 

A. the most prevalent element in quasars 

B. difficult to detect 

C. the oldest element in the universe 

D. the second-most abundant element in the universe

1
4 tháng 6 2017

Kiến thức: Đọc hiểu

Giải thích:

Theo đoạn văn, khí heli là ________

   A. nguyên tố phổ biến nhất trong chuẩn tinh B. khó để phát hiện

   C. nguyên tố lâu đời nhất trong vũ trụ           D. nguyên tố phong phú thứ hai trong vũ trụ

Thông tin: The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Tạm dịch: Các yếu tố ngoài Hydro và Heli tồn tại với số lượng nhỏ đến nỗi chính xác khi nói rằng theo trọng lượng, vũ trụ có phần hơn 25 phần trăm heli tính và phần nào ít hơn 75 phần trăm Hydro.

Chọn D

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

Most of the helium in the universe was formed ______ 

A. during the first minute of the universe's existence 

B. in a very short time 

C. in interstellar space 

D. before most of the hydrogen

1
8 tháng 4 2019

Kiến thức: Đọc hiểu

Giải thích:

Hầu hết helium trong vũ trụ được hình thành ______

   A. trong phút đầu tiên của sự tồn tại của vũ trụ                                B. trong một thời gian rất ngắn

   C. trong không gian giữa các vì sao               D. trước phần lớn hydro

Thông tin: However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist.

Tạm dịch: Tuy nhiên, khi vũ trụ hình thành chưa đầy một phút, Heli đã không thể tồn tại. Các tính toán cho thấy rằng trước khi nhiệt độ thời gian này là quá cao và các hạt của vật chất đã được di chuyển xung quanh nhiều quá nhanh. Chỉ sau mốc một phút Heli mới thể tồn tại.

Chọn B

Dịch bài đọc:

Các yếu tố ngoài Hydro và Heli tồn tại với số lượng nhỏ đến nỗi chính xác khi nói rằng theo trọng lượng, vũ trụ có phần hơn 25 phần trăm heli tính và phần nào ít hơn 75 phần trăm Hydro.

Các nhà thiên văn đã đo sự dư thừa của Heli khắp thiên hà của chúng ta và các thiên hà khác. Heli đã được tìm thấy trong những ngôi sao tồn tại đã lâu, ở những ngôi sao tương đối mới, trong khí giữa các vì sao, và trong các đối tượng ở xa gọi là chuẩn tinh. Hạt nhân helium cũng đã được tìm thấy là thành phần của các tia vũ trụ chiếu xuống Trái đất (tia vũ trụ không phải là thực sự là một dạng bức xạ, chúng gồm các hạt của nhiều loại khác nhau di chuyển nhanh chóng). Nó dường như không làm khác biệt đi nhiều nơi Heli được tìm thấy. Sự phong phú tương đối của nó dường như không bao giờ thay đổi nhiều. Ở một số nơi, có thể có nhiều hơn một chút; ở những nơi khác, một chút ít, nhưng tỷ lệ Heli trên các hạt nhân Hydro luôn luôn vẫn như nhau.

Helium được tạo ra trong các ngôi sao. Trong thực tế, phản ứng hạt nhân mà chuyển đổi Hydro thành Heli đảm nhiệm hầu hết năng lượng mà các ngôi sao tạo ra. Tuy nhiên, lượng Heli có thể đã được sản xuất theo cách này có thể được tính toán, và hóa ra là không có nhiều hơn một vài phần trăm. Vũ trụ đã không tồn tại đủ lâu để con số này là lớn hơn đáng kể. Do đó, nếu vũ trụ là có phần hơn 25 % Heli bây giờ, thì nó phải có được khoảng 25% Heli tại một thời điểm gần lúc nó hình thành.

Tuy nhiên, khi vũ trụ hình thành chưa đầy một phút, Heli đã không thể tồn tại. Các tính toán cho thấy rằng trước khi nhiệt độ thời gian này là quá cao và các hạt của vật chất đã được di chuyển xung quanh nhiều quá nhanh. Chỉ sau mốc một phút Heli mới thể tồn tại. Đến thời điểm này, vũ trụ đã quá nguội đến nỗi Nơtron và Proton có thể kết hợp vào nhau. Nhưng phản ứng hạt nhân dẫn đến sự hình thành của Heli đã hoàn thiện trong một thời gian tương đối ngắn. Sau khi vũ trụ được hình thành vài phút, việc tạo ra Heli đã không còn hiệu quả.

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

The word "they" refers to _____

A. particles 

B. cosmic rays 

C. constituents 

D. radiation 

1
25 tháng 11 2017

Kiến thức: Đọc hiểu

Giải thích:

Từ "they" dùng để chỉ _____

   A. hạt                          B. tia vũ trụ

   C. thành phần             D. bức xạ

Thông tin: cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds

Tạm dịch: tia vũ trụ không phải là thực sự là một dạng bức xạ, chúng gồm các hạt của nhiều loại khác nhau di chuyển nhanh chóng

Chọn B

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. The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen. Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in...
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.

The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.

Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic rays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn’t seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.

Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

What does the passage mainly explain? 

A. How stars produce energy 

B. When most of the helium in the universe was formed 

C. Why hydrogen is abundant 

D. The difference between helium and hydrogen 

1
19 tháng 10 2017

Kiến thức: Đọc hiểu

Giải thích:

Đoạn văn chủ yếu giải thích điều gì?

   A. Các vì sao tạo ra năng lượng như thế nào

   B. Thời điểm mà hầu hết khí heli trong vũ trụ được hình thành

   C. Tại sao hydro lại dồi dào

D. Sự khác biệt giữa heli và hydro

Thông tin: The universe has not existed long enough for this figure to be significant greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.

However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperature were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.

Tạm dịch: Vũ trụ đã không tồn tại đủ lâu để con số này là lớn hơn đáng kể. Do đó, nếu vũ trụ là có phần hơn 25 % Heli bây giờ, thì nó phải có được khoảng 25% Heli tại một thời điểm gần lúc nó hình thành.

Tuy nhiên, khi vũ trụ hình thành chưa đầy một phút, Heli đã không thể tồn tại. Các tính toán cho thấy rằng trước khi nhiệt độ thời gian này là quá cao và các hạt của vật chất đã được di chuyển xung quanh nhiều quá nhanh. Chỉ sau mốc một phút Heli mới thể tồn tại. Đến thời điểm này, vũ trụ đã quá nguội đến nỗi Nơtron và Proton có thể kết hợp vào nhau. Nhưng phản ứng hạt nhân dẫn đến sự hình thành của Heli đã hoàn thiện trong một thời gian tương đối ngắn. Sau khi vũ trụ được hình thành vài phút, việc tạo ra Heli đã không còn hiệu quả.

Chọn B 

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks. The Planets of Jupiter  The largest of the giant gas planets, Jupiter, with a volume 1,300 times greater than Earth’s, contains more than twice the mass of all the other planets combined. It is thought to be a gaseous and fluid planet without solid surfaces, Had it been somewhat more massive, Jupiter might have attained internal...
Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks.

The Planets of Jupiter

 The largest of the giant gas planets, Jupiter, with a volume 1,300 times greater than Earth’s, contains more than twice the mass of all the other planets combined. It is thought to be a gaseous and fluid planet without solid surfaces, Had it been somewhat more massive, Jupiter might have attained internal temperatures as high as the ignition point for nuclear reactions, and it would have flamed as a star in its own right. Jupiter and the other giant planets are of a low-density type quite distinct from the terrestrial planets: they are composed predominantly of such substances as hydrogen, helium, ammonia, and methane, unlike terrestrial planets. Much of Jupiter’s interior might be in the form of liquid, metallic hydrogen, Normally, hydrogen is a gas, but under pressures of millions of kilograms per square centimeter, which exist in the deep interior of Jupiter, the hydrogen atoms might lock together to form a liquid with the properties of a metal. Some scientists believe that the innermost core of Jupiter might be rocky, or metallic like the core of Earth.

 Jupiter rotates very fast, once every 9.8 hours. As a result, its clouds, which are composed largely of frozen and liquid ammonia, have been whipped into alternating dark and bright bands that circle the planet at different speeds in different latitudes. Jupiter’s puzzling Great Red Spot changes size as it hovers in the Southern Hemisphere. Scientists speculate it might be a gigantic hurricane, which because of its large size (the Earth could easily fit inside it), lasts for hundreds of years.

     Jupiter gives off twice as much heat as it receives from the Sun. Perhaps this is primeval heat or beat generated by the continued gravitational contraction of the planet. Another star like characteristic of Jupiter is its sixteen natural satellites, which, like a miniature model of the Solar System, decrease in density with distance from rocky moons close to Jupiter to icy moons farther away. If Jupiter were about 70 times more massive, it would have become a star, Jupiter is the best-preserved sample of the early solar nebula, and with its satellites, might contain the most important clues about the origin of the Solar System.

According to the passage, some scientists believe Jupiter and Earth are similar in that they both have__________.

A. solid surfaces      

B. similar masses           

C. similar atmospheres 

D. metallic cores

1
5 tháng 6 2017

Đáp án D

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks. The Planets of Jupiter  The largest of the giant gas planets, Jupiter, with a volume 1,300 times greater than Earth’s, contains more than twice the mass of all the other planets combined. It is thought to be a gaseous and fluid planet without solid surfaces, Had it been somewhat more massive, Jupiter might have attained internal...
Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks.

The Planets of Jupiter

 The largest of the giant gas planets, Jupiter, with a volume 1,300 times greater than Earth’s, contains more than twice the mass of all the other planets combined. It is thought to be a gaseous and fluid planet without solid surfaces, Had it been somewhat more massive, Jupiter might have attained internal temperatures as high as the ignition point for nuclear reactions, and it would have flamed as a star in its own right. Jupiter and the other giant planets are of a low-density type quite distinct from the terrestrial planets: they are composed predominantly of such substances as hydrogen, helium, ammonia, and methane, unlike terrestrial planets. Much of Jupiter’s interior might be in the form of liquid, metallic hydrogen, Normally, hydrogen is a gas, but under pressures of millions of kilograms per square centimeter, which exist in the deep interior of Jupiter, the hydrogen atoms might lock together to form a liquid with the properties of a metal. Some scientists believe that the innermost core of Jupiter might be rocky, or metallic like the core of Earth.

 Jupiter rotates very fast, once every 9.8 hours. As a result, its clouds, which are composed largely of frozen and liquid ammonia, have been whipped into alternating dark and bright bands that circle the planet at different speeds in different latitudes. Jupiter’s puzzling Great Red Spot changes size as it hovers in the Southern Hemisphere. Scientists speculate it might be a gigantic hurricane, which because of its large size (the Earth could easily fit inside it), lasts for hundreds of years.

     Jupiter gives off twice as much heat as it receives from the Sun. Perhaps this is primeval heat or beat generated by the continued gravitational contraction of the planet. Another star like characteristic of Jupiter is its sixteen natural satellites, which, like a miniature model of the Solar System, decrease in density with distance from rocky moons close to Jupiter to icy moons farther away. If Jupiter were about 70 times more massive, it would have become a star, Jupiter is the best-preserved sample of the early solar nebula, and with its satellites, might contain the most important clues about the origin of the Solar System.

It can be inferred from the passage that the appearance of alternating bands circling Jupiter is caused by__________.

A. the Great Red Spot

B. heat from the Sun

C. the planet’s fast rotation  

D. Storms from the planet’s Southern Hemisphere

1
15 tháng 2 2017

Đáp án C