____,I would have phoned you.

问题描述:

____,I would have phoned you.
A .If I know it B .Had I known it C .If I knew it D .Did I know it
为什么选B?为什么要用倒装,

这是一个虚拟语气的题目:主句I would have phoned you提示从句的时态应该是过去完成时,因此表达为if i had known it,而现把从句提前需要倒装所以变为Had I known it,I would have phoned you.现在你明白了吗?