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1、基础知识和基本语法点,巧记must,can,may表示“推测”的用法,首先请看下面的顺口溜：can不肯，may不问，must肯定不否问。这个顺口溜介绍了can(could),may(might),must 表“推测”时所适用的句式的区别。,其含义如下：can不肯，即：can(could)一般不用于肯定句；may不问，即：may(might)一 般不用于疑问句；must肯定不否问，即：must一般 仅用于肯定句，不用于 否定句和疑问句。,What does the writer find when he pushes his way through the crowd?,一、表示有把握的推测时，
2、肯定句用must(一定，准是)，否定句用cant(不可能，一定不)。must(cant)+动词原形，表示对现在情况的推测。must(cant)+be doing,表示对现在正在进行的情况的推测。must(cant)+have done，表示对过去情况的推测。,1。You must be hungry after a long walk.长途步行之后你一定饿了。2.They must be waiting for us.Lets hurry up.他们一定在等我们。让我们快点走吧。3.You must have left your bag in the theatre.你准是把你的包丢在剧院了。
3、,4.You cant be hungry,you have just had your dinner.你现在不可能觉得饿，你刚吃过饭。5.He wears glasses all the time,his eyesight cant be getting better.他一直带着眼镜，他的视力不可能在好转。6.He has no idea what the book is about,he cant have read it very carefully.他一点也不知道这本书是关于什么的，他一定没有仔细读过此书。,二、表示把握不大的推测即可能性时，用can和may，常译为“也许，可能”。ma
4、y用于肯定句与否定句，一般不用于疑问句。can常用于疑问句，一般不用于肯定句。例如：1.The news may or may not be true.这消息也许是真的，也许不是真的。2.At the moment she may be playing with her classmates.此刻她可能正在和同学们玩。,3.Anna might not have seen Tom yesterday.安哪昨天可能没有看见汤姆。4.Where can Wei Fang be?魏芳会在哪里呢？5.What can they be quarrelling about?他们可能在争吵些什么呢？6.Ca
5、n she have lost the book?她可能已把那本书丢了？,技能提高：,从A、B、C、D四个选项中，选出最佳选项。1Jenny _ with him at that time,for I was having dinner with her in my home.A.cant have been B.mustnt have been C.must have been D.may have been2.It is cold in the room.They _ have turned off the heating.A.must B.ought to C.should D.coul
6、d3.Someone is knocking at the door.Who _ it be at this hour of day?A.may B.can C.must D.should,A,B,4.I didnt hear the phone.I _ asleep.A.must be B.must have been C.should be D.should have been5.Johnson _ be a policeman.He is much too short.A.may B.mustnt C.should D.cant,B,D,6.Jack fell off a ladder
7、yesterday,but he was all right.He is lucky.He _ himself badly.A.can have hurt B.could have wounded C.might have hurt D.must have wounded7.Who told you the news?I dont remember clearly.It _ Mary.It _ Mary.She doesnt know it.A.may have been;cant be B.can be;mustnt be C.must have been;cant have been D.
8、may have been;may not be,C,A,情态动词+have+过去分词”的用法,英语中，表示对过去某种情况进行推测或对已发生的动作或存在的状态进行推测，常用情态动词must,may,might,can,could,should,ought to,would等 have 过去分词表示。一般来说，说话人的语气或推测的把握程度不同，使用的情态动词也不同。现分述如下：,1.must have 过去分词：表示对过去发生的动作或存在的状态进行推测。只用于肯定的陈述句中（在否定句及疑问句中用can）,意为“一定已经”。如：If he had really been there,I must
9、have seen him.如果他当时确实在那里，我一定会看见他了。Her watch must have stopped.I will go and call her.她的表准是停了。我去叫她。,2.may/might have 过去分词：表示对过去发生的动作或存在的状态进行不肯定的推测，即说话人认为过去某事发生的可能性或某状态存在的可能性不大。可用于肯定句(意思是“可能已经”)和否定句(意思是“可能没有”)；might的语气不如may那么肯定。如：She may have read the book.她可能已经看过这本书了。He might not have got your letter
10、.他或许没有收到你的来信。,3.can/could have 过去分词：表示对过去某种行为或存在的状态的 怀疑或不肯定推测。can常用于否定句(意思是“不可能已经”)和疑问句；could用于肯定句、否定句及疑问句,意思是“当时可能;本来可以”。如：Dont worry they could have just forgotten to phone.别担心他们很可能只是忘了打电话。Where can he have gone?他可能上哪儿去了？,4.need have 过去分词：该句式常用于否定句，表示过去做了不必做或不需要做的事情或过去做某事纯属多余，含有“根本不必；本来不必”之意，也可用于疑
11、问句。如：You neednt have told them that.你本不必要告诉他们那。Need they have done it last week?他们上周做这事有必要吗?,5.should/ought to have 过去分词：肯定式表示“过去本应做某事(但没做)”；否定式表示“过去不该做某事(但做了)”。该句式含有不满或责备之意。如：Youre right.I should have thought of that.你说得对。我本应当想到那点(但没想到)。She ought to have been more careful.她本该更小心些。,6.would have 过去分词
12、：表示过去本来要做某事却因某种原因未做，通常用来说明某种情况，但不像用should或ought to那样含有责备之意。如：I would have written to you earlier but I have been ill.我本来要早点给你写信，但我生病了。If I had seen the advertisement，I would have applied for the job.我要是看见那则广告的话，早就申请那份工作了。,高考链接：,1.He _ have completed his work,otherwise,he wouldnt be enjoying himself
13、by the seaside.(北京2题)A.should B.must C.wouldnt D.cant2.This cake is very sweet.You _ a lot of sugar in it.(05辽宁26题).Should put B.could have put C.might put D.must have put3.-Tom is never late for work.Why is he absent today?-Something _ to him.(05江西22题）A.must happen B.should have happened C.could ha
14、ve happened D.must have appened,4.I was on the highway when this car went past followed by a police car.They _ at least 150 kilometers an hour.(05重庆33题)A.should have been doing B.must have been doingC.could have done D.would have done5.I _have been more than six years old when the accident happened.(05天津14题)A.shouldnt B.couldnt C.mustnt D.neednt,Homework,
