表示对过去事情的否定推测，译成“不可能做过某事”。

1. Mr. Smith can't have gone to Beijing, for I saw him in the library just now. 史密斯先生不可能去北京了，我刚才还在图书馆见过他。

2. Mary can't have stolen your money. She has gone home. 玛丽不可能偷你的钱，她回家去了。

can+have+done

表示对过去行为的怀疑，用于疑问句，译成“可能做过……吗？”。

1. There is no light in the room. Can they have gone out? 屋里没有灯，他们可能出去了吗？

2. There is nowhere to find them. Where can they have gone? 到处找不到他们，他们可能到什么地方去呢？

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. 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。

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。

3 do you feel guilty when you have done something you shouldn't .

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。

would like to have done sth 本打算做某事

I would like to have read the article, but I was very busy then.

would rather +have done 当时宁愿做了 或没做

I would rather have refuse his offele