23. Since 1965 there are four times as many Black college students enrolled, and the one million Black people in college today represent 11 percent of all college students.

(A) Since 1965 there are four times as many Black college students enrolled

(B) The enrollment of Black college students was only one-fourth in 1965

(C) The enrollment of Black college students has increased four times from 1965 on

(D) Quadrupling since 1965, there are now four times as many Black college students enrolled（E）

(E) The enrollment of Black college students has quadrupled since 1965

The comparison in A is incomplete: the reader may be left wondering, four times as many as what? B, also incomplete, would have to say something like “one-fourth of the present enrollment” to make clear sense. Taken out of context, the meaning of C is uncertain: C could be read as saying that the enrollment of Black college students has increased fourfold or that it has increased four different times. D presents a dangling modifier because there is no noun in the main clause that Quadrupling since 1965 can modify: Black college students have not quadrupled since 1965; their enrollment has. E states the idea clearly and correctly. The question is moderately easy.

对于ets选项c的解释是不是说four times 既有4倍的意思，也有4次的意思，所以uncertain.

第一个问题：times既有倍数也有次数的意思，是不是会引起歧义呢？

而对于d，我认为是逻辑主语没有的问题，ets说main clause 中没有noun that quadrupling since 1965 can modify，这个modify怎么解释呢，longman 的解释说是修饰的意思(if an adjective, adverb etc modifies another word, it describes something or limits the word's meaning. In the phrase 'walk slowly', the adverb 'slowly' modifies the verb 'walk')，问题是这种分词做状语应该是修饰主句动词亚，

第二个问题：如果该句中有了一个noun 可以被modify的话是不是就对了呢？下面这个对不对？

谢谢