15. Why does the author mention cosmic rays in line 7?
(A)As part of a list of things containing helium
(B) As an example of an unsolved astronomical puzzle
(C) To explain how the universe began
(D) To explain the abundance of hydrogen in the universe
16. The word vary in line 10 is closest ill meaning to
(A) mean
(B) stretch
(C) change
(D) include
17. The creation of helium within stars
(A) cannot be measured
(B) produces energy
(C) produces hydrogen as a by-product
(D) causes helium to be much more abundant In old stars than In young star:
18. The word calculated in line 15 is closest in meaning to
(A) ignored
(B) converted
(C) increased
(D) determined
19. Most of the helium in the universe was formed
(A) in interstellar space
(B) in a very short time
(C) during the first minute of the universes existence
(D) before most of the hydrogen
20. The word ceased in line 26 is closest in meaning to
【托福考试:TOEFL模拟试题】相关文章:
最新
2016-03-02
2016-03-02
2016-03-02
2016-03-02
2016-03-02
2016-03-02