约翰不在家，我想他可能去上学了吧。

　　You might have read about it in the papers.

　　你可能已经在报纸上看到这个消息了。

　　[名师点津]　might have done有时表示 "本来可以做的事而实际上没有做"，含有 "劝告，责备"的语气。

　　You might have been more careful.

　　你本来可以多加小心的。

　　2．must have done sth.表示对过去发生的事或行为的肯定推测，意为"一定做过某事"，只用于肯定句中。

　　He reasoned that since she had not answered his letter she must have left here.

　　他推断，由于她没有给他回信，她一定是已经离开这里了。

　　[名师点津]　含有must have done结构的反意疑问句中，若有表示过去的时间状语，反意疑问部分用"didn't＋主语？"；若没有表示过去的时间状语，反意疑问部分则用"haven't/hasn't＋主语？"。

　　They must have gone there last night, didn't they?

　　他们昨晚一定是去那里了，不是吗？

　　They must have been to the Great Wall, haven't they?

　　他们一定去过长城，不是吗？

　　3．can/could have done sth.是对过去的推测，表示"可能做过某事"，主要用于否定句和疑问句中。could语气较委婉，肯定句中一般用could不用can。

　　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。

　　- Where can they have gone?

　　- They could have gone to the cinema.

　　--他们能去哪里呢？

　　--他们可能去电影院了。

　　[名师点津]　could have done sth.还可表示过去本可以完成而实际上未完成的动作。

　　You could have done better，but you were too careless.

　　你本来可以做得更好，但你太粗心了。

　　[即时演练1]

　　(1)用适当的情态动词填空

　　①(2016·浙江高考)George can't have gone too far.His coffee is still warm.

　　②-We are very worried about Tom. Why hasn't he come back?

-Don't worry. He may/might have been caught in a traffic jam.