题目内容：

_____an hour earlier,Mary wouldn't have been caught in the heavy rain.
A.if she has returned
B.had if she return
C.had she returned
D.if she returned 为什么选C?

优质解答

这句是省略if的虚拟语气,在if引导的条件状语从句中,如果提前则if可以省略,并且构成倒装句式,而且是表示与过去事实相反的假设,所以选C.