Question

虚拟语气 i didn't know his telephone number.____ it, I ______ then

i didn't know his telephone number.____ it, I ______ then

A. Had I known; would ring him up
B. Should I know ;would have ring him up
C. If I knew ;would ring him up
D. Had I know; would have rung him up

Answer 1

A
这个~~~虚拟语气其实也很好理解的。这样想吧。
前面用的过去时，他假设过去的时候他知道电话号码，那么那个时候他将会给他打电话。
所以前面是Had I known，正确的语序是I had known，这是过去完成时，假设在过去我已经知道了他的号码。
I would do ，应该是接当时的情况，我如果当时知道了号码，我将会做那件事。第4个选项，意思是我将会已经完成了某件事，跟语境是不符合的。