情态动词 + have done
一． “情态动词 + have + done”，表示对过去的行为或动作进行推测。
1. “must have done”表示对过去事情的肯定推测，翻译成“一定做过某事”。
没有mustn’t have done这一用法。其相对应的否定或疑问句中用的形式是
“can’t/couldn’t have done”,翻译为“不可能做过某事”。
如; ----Tom often touches people’s stuff without permission. Yesterday he came to my home.
He must have touched my things. I don’t like him.
----He can’t have touched your things because your room was locked.
2. “may / might have done”表示对过去事情的不确定的推测，翻译成“过去可能做了某事”。
may 比 might 表示的可能性在说话人看来稍大些。
其相对应的否定形式是may/might not have done，表示“过去可能没有做某事。
” may/might have done表推测不用于疑问句中。
如： ----He may have heard everything I just said.
----Don’t worry. He may not have heard it.
3. “can/could have done” 表推测一般用在否定句和疑问句中，表示不相信或怀疑的态度。
如： ----Can/Could she have heard the truth that day?
----I think she can’t/couldn’t have heard it because she looked normal.
二． “情态动词 + have + done”的虚拟语气的用法。
1. could have done, 表示“过去本能够做某事却未做。”
注：其否定形式 couldn't have done 没有虚拟语气的用法.
如； I could have saved her, but I was too scared. I’m so sorry.
2. Might have done, 表示“过去本可以做某事却未做。”
注：其否定形式 might not have done 没有虚拟语气的用法.
如： I might have saved her. It’s hard to say.
3. needn't have done 表示 “过去本不需要做某事却做了。”
一般来说need have done这种形式用的很少。
如：You are so polite. You needn’t have bought so many things.
You needn’t have come here personally.
4. should have done , 表示“过去本应该做某事却未做。”
注：其否定结构 shouldn't have done 表示 “过去本不该做某事却做了。”
如： You should have finished your homework.
He should not have done that. It was too stupid.
5. Would have done, 表示“过去本来会做某事却没做”.
注：其否定结构wouldn’t have done表示“过去本不会做某事却做了”。
如： I would have attended the sports meeting, but because my foot was injured, I didn’t.
I wouldn’t have killed the spider, but he forced me to do that.
1. I was really anxious about you. You_________ home without a word.
A. mustn't leave B. shouldn't have left
C. couldn't have left D. needn't leave
2. — I’ll tell Mary about her new job tomorrow.
— You________ her last week.
A．ought to tell B．would have told
C．must tell D．should have told
3. He _______ have completed his work; otherwise, he wouldn't be enjoying himself by the seaside.
A. should B. must C. wouldn't D. can't
4. — Do you know where David is? I couldn't find him anywhere.
— Well. He _______have gone far, for his coat's still here.
A．shouldn't B．mustn't C．can't D．wouldn't