高中英语情态动词 have-done的用法(共18张PPT)

“情态动词+have done”的用法 　一、 “must have done” 一定做过某事 表示对过去事情的肯定推测，该结构只用于肯定句。 1. It must have rained last night, for the ground is wet. 昨晚一定下雨了，因为地面还是湿的。 　2. You must have been mad to speak to the servant. 你和仆人说话，一定是发疯了。 二、 “can’t have done” “couldn’t have done” 不可能做过某事 表示对过去事情的否定推测，“couldn’t have done”较少使用。 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。 　三、 “could have done” 1)表示猜测，“过去可能做过某事”,多用于疑问句； 2)用于虚拟语气，意思是“本来能够做某事而没有做”。　 What could have happened? 难道可能发生了什么事吗？ This glass is cracked. Someone could have dropped it. 这个玻璃杯破了。可能是谁把它掉在地上了。 　He could have passed the exam, but he was too careless. 本来他能够通过考试，但是他太粗心。 “can… have done” 表示对发生过的事情的推测，用于疑问句中。 It`s so late. Where can she have gone? 天晚了，她可能去哪儿了呢？ 四、 “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