情态动词加have+done的用法

“must+have+done”表示对过去事情的肯定推测，译成“一定做过某事”，该结构只用于肯定句。

“cant+have+done”表示对过去事情的否定推测，译成“不可能做过某事”。

“could+have+done”是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做。

“may+have+done”表示对发生过的事情的推测，意思是“可能已经”或“也许已经”，用于肯定句中。

—What has happened to George?

—I don't know. He may have got lost.

—乔治发生了什么事？

——我不知道，他可能迷路了。

“might+have+done”表示对过去事情的推测，might与may意思相同，但可能性更小。多用于虚拟语气结构中。

1. He might have given you more help, even though he was busy. (MET90) 他或许会多给你一些帮助，即使他很忙。

2. She might have achieved greater progress, if you had given her more chances. 如果你多给她点机会，她可能已经取得更大的成绩。

“would+have+done”虚拟语气，表示对过去事情的假设，意思是“本来会做”。

1. I would have told you all about the boy's story, but you didn't ask me. 我本来会告诉你这个小男孩的故事，但是你没有问我。

2. Without your help, I wouldn't have achieved so much. 没有你的帮助，我是不会取得如此大的成绩。

“should+have+done”意思是“本来应该做某事，而实际没做。” “shouldn't+have+done”表示本来不应该做某事，而实际做了。含有指责对方或自责的含意。

1. Tom, you are too lazy. The work should have been finished yesterday. 汤姆，你太懒惰了，这项工作本来应该昨天就做完的。

2. Look, Tom is crying. I shouldn't have been so harsh on him. 看，汤姆哭了，我本来不应该对他如此严厉。

“ought to+have+done”表示过去应该做而实际并没有做，译成“理应做……”，往往表示遗憾。与“should+have+done”用法基本一样。

I ought to have gone home last Sunday. 我理应上星期日回家。

You ought not to have given him more help. 你不应该帮助他那么多。

“need+have+done”表示本来需要做某事而没有做。“needn't+have+done”则表示“本来不需要做某事而做了”。

I needn't have bought so much wine—only five people came. 我本来没有必要买这么多酒，只来了五个人。

He need have hurried to the station. In that case, be wouldn't have missed the train. 他本来需要快点去车站，那样的话，他就不会误了火车。