英语语法：I could have fooled you.情态动词+完成时形成虚拟语气用法，本来可以作但没做，但今天人说

I might have killed a man last night.是表猜测，奇怪了，情态动词换了个就不是虚拟了？而且last night是过去，这里该用完成时？情态动词+动词的句子有过去时和进行时吗？

你好。
1 I might have killed a man last night.是表猜测== It is possible that I killed a man last night.

2 I could have fooled you (if I had wanted to). -------这是虚拟语气，假设过去的事情。一般来说，情态动词 + 完成式 -------指代已经过去的事情。
it was possible that she was writing at that time == She might be writing at that time 情态动词+进行式。
it was possible that she was a nurse at that time == she might be a nurse at that time 情态动词+过去式------这个“过去式”体现在“情态动词”上面：may --- might

建议吗一本语法书把虚拟语气哪一章好好看一下，这里一两句话说不清

i could have fooled you。可以忽悠你，但没有。fool是个unreal action，so 虚拟。 i might have killed。他可能死也可能没有。kill action may be true，so非虚拟。

情态动词 have done.既可以表示对过去进行猜测又可以表示虚拟语气。 表虚拟语气时，should have done=ought to have done本应该做而没做;would have done本来就会去做而没做；could have done本可以做而没做；might have done本可能/可以做而没做。表对过去猜测时，must have done一定做过某事，否定形式：cannot have done.例：she must have come here last night.她一定是昨晚来的；she cannot have gone there.她不可能到那里去。may have done可能做过某事，否定形式：may not have done

'情态动词+完成时'表对过去的'评价或猜测",具体译法要根据所用的情态动词的意思,should"应该'might'可能'could'能,会(表能力)must '一定,一准'(猜测),学习语言尽量不要机械性的照搬应该对照语境以理解为主.你说的第一个句子是指当时'本来能够做到";第二句是说可能性 情态动词后接过去式的肯定没有,至于,Hurry,he must be waiting for us. (他现在一定在等我们)