課本中不會教你的[M]479　must/may/might/can't/couldn't have done

479　must/may/might/can't/couldn't have done

◎ 本句型用于對過去的推測，must have done意為“過去一定做了某事”；may/might have done表示“過去可能做了某事”；can't/couldn't have done表示“不可能已經做了某事”；本句型的疑問句和否定句要用can或could。在此句型中，用may和can語氣較強，用might和could語氣較弱，并無時態(tài)之分。

Jim lookes tired out. He must have sat up too late last night. 吉姆看上去非常疲憊，他昨晚一定睡得太遲了。

The light in his room is out. He might/may have gone to bed. 他房間里的燈熄了，他可能已經睡了。

You can't/couldn't have seen her yesterday. She went on an expedition a few days ago. 你昨天不可能看到她的，她幾天前外出探險去了。

Frank looks worried. What may have happened to him？弗蘭克看上去憂心忡忡的。他可能發(fā)生了什么事？