It is clever _____ you _____ such an important question.

题目

It is clever _____ you _____ such an important question.
A.for,to ask B.for,asking
C.of,to ask D.of,asking
为什么？

答案

选A
这是一个动词不定式做主语的句子,to ask such an important question
实际上是作主语,it只是替代,避免句子出现头重脚轻.for是指对谁而言,for you 是说对你来说.