In the last ten years, the dropout rate among Black high school students fell substantially over the past decade, while the number of Blacks who attend college is more than twice what it was. A. fell substantially over the past decade, while the number of Blacks who attend college is more than twice what it was. B. fell substantially, while the number of Blacks attending college is more than double what it was at that time. C. has fallen substantially, while the number of Blacks attending college has more than doubled. D. has fallen substantially over the past decades, while the number of Blacks attending college is more than twice what it was at that time. E. has fallen substantially over the past decades, while the number of Blacks who are attending college are more than double what they are.
请教新东方蓝书上的一题语法,我选C,但答案是E.由于这本书上的答案常有错,所以我想请问一下大家选的是什么,理由又是什么?谢谢. | 
