[求助]大全51题

51、        According to surveys by the National Institute on Drug Abuse, about 20

percent of young adults used cocaine in 1979, doubling those reported in the

1977 survey.

(A) doubling those reported in the 1977 survey

(B) to double the number the 1977 survey reported

(C) twice those the 1977 survey reported

(D) twice as much as those reported in the 1977 survey

(E) twice the number reported in the 1977 survey

答案选（E）,请问在句子中做何成分？如果把它看成一个省略 which is 的定语从句，which 则指代about 20 percent of young adults used cocaine in 1979。我记得好像在GMAT中 which 是不能指代一个句子的。迷惑！ 敬请高手指点！

第一次提问，多多包涵！感谢！

偶觉得就是前面整个一段话对后面造成的影响。不可以看成which is的省略结构。看成独立主格结构更好些吧。不确定的说。

应该是 about 20 percent 的同谓语作补充解释说明的吧~~i　thinke so .