1、一、 “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。 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、 “cant+have+done” 表示对过去事情的否定推测，译成“不可能做过某事” 。1. Mr. Smith cant have gone to Beijing, for I saw him in th
2、e 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 cant have stolen your money. She has gone home. 玛丽不可能偷你的钱，她回家去了。三、 “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
3、处找不到他们，他们可能到什么地方去呢？四、 “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。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。五、 “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 dont know. He may have got lost.乔治发生了什么事？我不知道，他可能迷路了。六、 “might+hav
4、e+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。七、 “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 w
5、ould have told you all about the boys story, but you didnt 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 wouldnt have achieved so much. 没有你的帮助，我是不会取得如此大的成绩。八、 “should+have+done” 意思是“本来 应该做某事，而 实际没做。 ” “shouldnt+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 shou
6、ld 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 shouldnt have been so harsh on him. 看， 汤姆哭了，我本来不应该对他如此严厉。九、 “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
7、 him more help. 你不应该帮助他那么多。十、 “need+have+done” 表示本来需要做某事而没有做。 “neednt+have+done”则表示“ 本来不需要做某事而做了”。I neednt have bought so much wineonly 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 wouldnt 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。高考题 【经典考例 1】 The
8、 weather turned out to be fine yesterday. I _ the trouble to carry my umbrella with me. (2006 江西)A. should have taken B. could have taken C. neednt have taken D. mustnt have taken【经典考例 2】 We _ have proved great adventurers, but we have done the greatest march ever made in the past ten years. (2006 天
9、津)A. neednt B. may not C. shouldnt D. mustnt【经典考例 3】 As you worked late yesterday, you _ have come this morning. （2006 陕西）A. maynt B. cant C. mustnt D. neednt一、在虚拟语气中的用法1. should have done 表示“过去本应该做某事却未做。 ”其否定结构 shouldnt have done 表示 “过去本不该做某事却做了。 ”2. ought to have done 表示“过去本应该做某事却未做。 ”其否定结构 oughtn
10、t to have done 表示 “过去本不该做某事却做了。 ”3. need have done 表示“过去本有必要做某事却未做。 ”其否定结构 neednt have done 表示 “过去本没必要做某事却做了。 ”4. could (不能用 can) have done 表示“过去本能够做某事却未做。 ”注意：其否定形式 couldnt have done 没有虚拟语气的用法，couldnt have done 只能表推测，相当于 cant have done，意为：“过去不可能做了某事。 ”5. might (不能用 may) have done 表示“过去本可以做某事却未做。 ”
11、注意：其否定形式 might not have done 没有虚拟语气的用法，might not have done 只能表推测，相当于 may not have done，意为：“过去可能没有做某事。 ”二、表推测的用法1. must have done表示对过去某事的肯定猜测，译为：过去肯定做了某事。不存在 mustnt have done 的形式。其否定或疑问形式须用 can(could) 来表示. 例如：Since the road is wet, it must have rained last night. 既然路是湿的，那昨天晚上肯定下雨了。He cant have missed
12、 the way. I drew him a map. 他不可能迷路。我（当时）给他画了张图。“The dictionary has disappeared. Who could have taken it?” 词典不见了，（过去）谁可能把它拿走了？2. may / might have donemay / might have done 表示“过去可能做了某事” 。may 比 might 表示的可能性在说话人看来稍大些。may/might not have done 表示“过去可能没有做某事。 ”例如：I cant find my keys. I may / might have left
13、them at the school yesterday. 我找不到我的钥匙了。我可能昨天把他们落在学校了。John may/might not have passed the exam; he looks very sad.约翰可能没有通过考试。他看起来很忧伤。注意：may/might have done 表推测不能用于疑问句中。3. can/could have done 表推测一般用在否定句和疑问句中，表示不相信或怀疑的态度。Can/Could he have passed the exam?他可能通过了考试吗？I think that he couldnt/cant have gone
14、 abroad. I saw him just now.我认为他不可能出国了。我刚才还看见他了。注：表示推测过去某动作发生的可能性时，就表示的可能性程度而言，must 最大，could 其次，may 更次之，might 最小。例如：“I wonder how Tom knew about your past.” “我想知道汤姆是怎么知道你的过去的。 ”“He must / could / may / might have heard of it from Mary.” “他肯定/很可能/可能/兴许（没准儿）已从玛丽那儿听说此事了。 ”三、高考例析1. Sorry Im late. I _ ha
15、ve turned off the alarm clock and gone back to sleep again.（2000 北京春季）A. might B. should C. can D. will答案为 A。表推测的用法。句意：对不起，我迟到了。我（当时）兴许是关了闹钟又回去睡觉了。might 相当于 may, 但语气更加不肯定。2. I was really anxious about you. You_ home without a word. （01 全国）A. mustnt leave B. shouldnt have left C. couldnt have left D.
16、 neednt leave答案为 B。虚拟语气用法。句意：我（那时）真地很担心你。你本不应该不留个话就离开家。3. Ill tell Mary about her new job tomorrow. You_ her last week. （04 福建）Aought to tell Bwould have told Cmust tell Dshould have told答案为 D。虚拟语气用法。句意：-我明天要告诉她我的新工作的情况。 -你本应该上周告诉她。4. Tom graduated from college at a very young age. Oh, he _ have bee
17、n a very smart boy then. （04 全国 IV）A. could B. should C. might D. must答案为 D。表推测的用法。句意：汤姆很年轻的时候就大学毕业了。哦，他肯定是一个很聪明的男孩儿。5. He _ have completed his work; otherwise, he wouldnt be enjoying himself by the seaside. (05 北京卷)A. should B. must C. wouldnt D. cant答案为 B。用法同4题。句意：他肯定做完了工作，不然他就不会在海边痛快地玩儿了。6. Do you know where David is? I couldnt find him anywhere. Well. He have gone farhis coats still here. （05湖北卷）Ashouldnt Bmustnt Ccant Dwouldnt答案为 C。表推测的用法。句意：你知道大卫在哪儿吗？我哪儿也找不到他。瞧，他不可能走远他的上衣还在这儿呢。cant 相当与 couldnt，但后者语气更加委婉。
