¡¡¡¡13.According to the passage£¬ helium is
¡¡¡¡£¨A£© the second-most abundant element in the universe
¡¡¡¡£¨B£© difficult to detect
¡¡¡¡£¨C£© the oldest element in the universe
¡¡¡¡£¨D£© the most prevalent element in quasars
¡¡¡¡14.The word "constituents" in line 9 is closest in meaning to
¡¡¡¡£¨A£© relatives
¡¡¡¡£¨B£© causes
¡¡¡¡£¨C£©components
¡¡¡¡£¨D£© targets
¡¡¡¡15.Why does the author mention "cosmic rays t in line 10£¿
¡¡¡¡£¨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 14 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£º
¡¡¡¡18. The word "calculated" in line 20 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 universe s existence
¡¡¡¡£¨D£© before most of the hydrogen
¡¡¡¡20.The word "ceased" in line 35 is closest in meaning to
¡¡¡¡£¨A£©extended
¡¡¡¡£¨B£©performed
¡¡¡¡£¨C£©taken hold
¡¡¡¡£¨D£©stopped
¡¡¡¡Questions 21-30
¡¡¡¡In colonial America£¬ people generally covered their beds with decorative quilts resembling those of the lands from which the quitters had come. Wealthy and socially prominent settlers made quilts of the English type£¬ cut from large lengths of cloth of the same color and texture rather than stitched together from smaller pieces. They mad these until the advent of the Revolutionary War in I 775£¬ when everything English came to be frowned upon.
