1、1情态动词情态动词表示推测表示推测不表示推测不表示推测can couldmay mightshall shouldmust will wouldought tohave to dare (darent)need (neednt)used to2情态动词有一定的意义，但没有人称和数的情态动词有一定的意义，但没有人称和数的变化，不能独立使用，它和后面的动词构成变化，不能独立使用，它和后面的动词构成谓语谓语只作情态动词的只作情态动词的can/could,may/might,ought to，must可情态可实义的可情态可实义的need,dare/dared可情态可助动词的可情态可助动词的shall/
2、should,will/would相当于情态动词的相当于情态动词的have to,used to3must,can/could,may/might 的用法的用法must1.must 表示推测时，表示推测时，只能用于肯定句。只能用于肯定句。e.g.这个电脑肯定出了问题。这个电脑肯定出了问题。There must be something wrong with the computer.你努力学了一整天，你努力学了一整天，一定累了吧一定累了吧You have worked hard all day.You must be tired.42.must+be doing/do 表示对表示对现在的动作现
3、在的动作进行进行肯定推测肯定推测 e.g.他现在一定在看小说他现在一定在看小说.He must be reading novels now.他们买了一辆新车他们买了一辆新车。他们一定很有钱他们一定很有钱.They have bought a new car.They must have a lot of money.53.must+have done 表示对表示对过去发生的事情过去发生的事情作作出的肯定判断出的肯定判断e.g.e.g.他们在玩篮球，他们在玩篮球，他们一定完成了作业。他们一定完成了作业。They are playing basketball,they must have fini
4、shed their homework.路是湿的。昨天晚上一定下雨了。路是湿的。昨天晚上一定下雨了。The road is wet.It must have rained last night.6对现在或将来情况推测：对现在或将来情况推测：must+动词原形。动词原形。must只能用于肯定。否定和疑问分别用只能用于肯定。否定和疑问分别用cant和和can。e.g.He must tell a lie.Can he tell a lie?He cant tell a lie.*must-should/ought to may-might/could+do可能性依次减弱可能性依次减弱78He mu
5、st be reading,isnt he?You must do it yourself,dont you?He must have gone over the article,hasnt he?It must have rained last night,didnt it?表猜测语气的反意疑问句的构成表猜测语气的反意疑问句的构成9can/could 1.can/could 表示推测时，只能用在表示推测时，只能用在否定句否定句或疑问句中或疑问句中。e.g.Its so late.Can Tom be reading?Can it be Mr.Green?这个人不可能是玛丽，这个人不可能是玛丽
6、，她生病了。她生病了。It cant be Mary.She has fallen ill.她不可能在说谎。她不可能在说谎。She couldnt be telling lies.102.can/could have done 对对过去发生过去发生行为的可行为的可能性进行推测能性进行推测:刚才我还看见他了，刚才我还看见他了，所以他不可能出国的。所以他不可能出国的。I saw him just now so he couldnt have gone abroad.门是锁着的，门是锁着的，所以她不可能在家。所以她不可能在家。The door was locked.She couldnt have
7、been at home.113.can/could have done“本可以，本来可能本可以，本来可能已经已经”用于肯定句中，表示对过去发生的事用于肯定句中，表示对过去发生的事情做出的判断情做出的判断.e.g.你本来可以考的更好。你本来可以考的更好。You could have had a better mark.12may/might1.may/might表示推测时，只能用于陈述句，表示推测时，只能用于陈述句，表示对现在或将来要发生的动作把握不大。表示对现在或将来要发生的动作把握不大。e.g.她们明天可能会到这里来。她们明天可能会到这里来。They may come here tomor
8、row.他们可能还在等我们呢。他们可能还在等我们呢。They may be still waiting for us.133.might/may have done,表示对过去发生的动表示对过去发生的动作进行可能性推测。作进行可能性推测。e.g.他可能去医务室了。他可能去医务室了。He may have gone to the clinic.他可能已经从报纸上知道这个消息了。他可能已经从报纸上知道这个消息了。He might have read about the news in the newspaper.14用于表达合理推断。用于表达合理推断。e.g.It is three oclock,
9、the football game should begin now.Mary took dancing lessons for years,she should be an excellent dancer.2.should 的用法的用法15表示推测表示推测情态动词的重要用法情态动词的重要用法.肯定的推测肯定的推测可能的推测可能的推测否定的推测否定的推测疑问的推测疑问的推测must 对将来对将来 对现在对现在 对过去对过去情态动词情态动词may,might cant,couldntcan,could +V.+V.+have done常见常见must be +be doing +V.+V.+h
10、ave done +be doing 可以用可以用not表示表示“可能不可能不”+V.+V.+have done +be doing+V.+V.+have done +be doing161.Judging from his accident,he must be from the south,2.Tom bought a lot of apples.He must like eating apples,3.It is eleven oclock at night and the lights are off.They must be sleeping now,isnt,he?didnt he
11、?arent they?因因must后是实意动词后是实意动词like因因must后是系动词后是系动词 be must后接的是后接的是be sleeping，是对正在进，是对正在进行的情况推测行的情况推测171.We must have learned 2,000 words by the end of last term,hadnt we?3.He must have gone to Beijing,didnt it?hasnt he?若句中含有过去完成时的时间状语，用过去完成时完成反意疑问句若句中含有过去完成时的时间状语，用过去完成时完成反意疑问句若句中含有过去的时间状语，用一般过去时完成反
12、意疑问句若句中含有过去的时间状语，用一般过去时完成反意疑问句若句中不含任何时间状语，若句中不含任何时间状语，用现在完成时完成反意疑问句用现在完成时完成反意疑问句2.It must have rained last night,for the road was very muddy，18 1.I dont know where she is,she _ be in Wuhan.2.At this moment,our teacher _ our exam papers.这时，我们老师想必在批改试卷。这时，我们老师想必在批改试卷。3.The road is wet.It _ last night.
13、(rain)4.Your mother _ for you.你妈妈一定一直在找你。你妈妈一定一直在找你。maymust be markingmust have rainedmust have been looking195.Philip _ seriously in the car accident.菲利普可能在车祸中受了重伤菲利普可能在车祸中受了重伤.6.-Linda has gone to work,but her bicycle is still here.-She _(go)by bus.7.Mike _ his car,for he came to work by bus this
14、morning.迈克一定还没有找回他的车，因为早上他是坐迈克一定还没有找回他的车，因为早上他是坐 公共汽车来上班的。公共汽车来上班的。may(might)have been hurtmay(might)have gonecant have found20Practice 2:表示推测表示推测情态动词的重要用法情态动词的重要用法.1.You must be Mr Smith-I was told to expect you here.2.He must have known what we wanted.3.We may have read the same report.4.He cant h
15、ave slept through all that noise.5.Theres someone outside-who can it be?6.What can they be doing?7.These pills might help to cure your disease.8.You could be right,I suppose.211.-Is John coming by train?-He should,but he _ not.He likes driving his car.(2002高考题）高考题）A.must B.can C.need D.may2.It has b
16、een announced that candidates(候选人候选人)_ remain in their seats until all the papers have been collected.(2002上海上海高考题）高考题）A.can B.will C.may D.shall3.-I heard they went skiing in the mountains last winter.(2002北京北京高考题）高考题）-It _ true because there was little snow there.A.may not be B.wont be C.couldnt b
17、e D.mustnt be22modal verbGrammar(33ms)23could(不用can)+have done,在肯定句中表示“本来能够而没能”，具有婉转的批评和责备之意。1.I could have passed my exam easily,but I made too many stupid mistakes.我本来能够轻易通过考试，但我犯了太多不该我本来能够轻易通过考试，但我犯了太多不该 犯的犯的错误。错误。2.You could have reported to me earlier.你本该早点告诉我的。你本该早点告诉我的。24should/ought to+have
18、done用于肯定句时，表示“本该做某事而实际上没做”，用于否定句时，则表示“不该做的事反而做了”。1.You should have told him a week ago.你本来应该在一周前告诉他的。你本来应该在一周前告诉他的。2.You ought not to have taken the magazine out of the reading room.他不该、把杂志带出阅览室的。他不该、把杂志带出阅览室的。25might（不用may）+have done表示“本来可能”，但实际上没有发生的事。另外，还可表示“本来应该或可以做某事”之意，含有轻微的责备语气。1.You might no
19、t have told her.你本可以不告诉他的。（事实上你告诉他了）你本可以不告诉他的。（事实上你告诉他了）2.You might have come earlier.你本可以早点来的。（但没有这样）你本可以早点来的。（但没有这样）26neednt+have done表示做了本表示做了本来不必去做的事。来不必去做的事。1.She neednt have gone to the station yesterday.昨天她本不必到火车站去的昨天她本不必到火车站去的.（昨天她去了）（昨天她去了）2.You neednt have bought it.你本可不必买它的。你本可不必买它的。（你买了）
20、（你买了）27巩巩 固固 练练 习习 1.Oh,Im not feeling well in the stomach.I _ so much fried chicken just now.A.shouldnt eat B.shouldnt have eaten C.mustnt eat D.mustnt have eaten2.-Why hasnt Jane arrived yet?-She _ again in the morning?A.shouldnt have overslept B.may have turned off the alarm clockC.must have no o
21、ne t o call herD.should have someone to wake her up3.-Did you go to the movie the day before yesterday?-No.We _,but we decided not to.A.should have gone B.could go C.should go D.could have goneBBA284.As it turned out to be a small house party,we _ so formally.neednt dress B.didnt have to dress upC.M
22、ight not have dressed up D.neednt have dressed up5.Im rather surprised you havent reported him to your teacher.In my opinion,you _ this as soon as you found out he was cheating.must have done B.might have done C.should have done D.could have done DC292.should 的用法的用法注意：注意：should可表示可表示“居然，竟然居然，竟然”。e.g
23、.我不敢相信这样一个绅士居然对老人如此我不敢相信这样一个绅士居然对老人如此无礼。无礼。I cant believe such a gentleman should be so rude to the old.30e.g.Young people should learn how to use computers.Every citizen ought to obey law.You ought not to go.3.should常表示劝告、建议、命令，与常表示劝告、建议、命令，与ought to意义相近，但意义相近，但ought to多表示责任、多表示责任、义务，语气强烈。在疑问句中通常用义
24、务，语气强烈。在疑问句中通常用should代替代替ought to。31e.g.You should/ought to have told her the truth earlier.She shouldnt have left without saying a word.4.should/ought to have done表示责备或表示责备或批评批评,意为意为“本应该做到本应该做到但没有做到但没有做到”,用用于否定则表示于否定则表示“本不该本不该但但”ought to的语的语气更强烈气更强烈.32can,could 和和be able to的用法的用法e.g.She can/be able
25、 to sing the song in English.This machine can make you feel comfortable.1.can,be able to都可表示都可表示“能力能力”Can的主语是人或物的主语是人或物,be able to的主语是人的主语是人 33can,could 和和be able to的用法的用法e.g.Well be able to finish the work soon.I havent been able to see the film.2.can只用于现在时和过去时只用于现在时和过去时(could)。be able to可以用于各种时态。可
26、以用于各种时态。could用于表示泛指过去的能力。用于表示泛指过去的能力。e.g.I could read when I was four.34Although the soldier was badly wounded,he was able to tell what had happened.3.表示特定的某一过去能力或表示成功地做表示特定的某一过去能力或表示成功地做了某事时，只能用了某事时，只能用was/were able to，不能不能用用could。e.g.He was able to escape from Europe before the war broke out.He was able to swim before he got tired.表示过去的能力表示过去的能力354）may 表示许可，表示允许别人做某事，表示许可，表示允许别人做某事，也可征求对方的许可。也可征求对方的许可。May I open the door?We may keep the book for two weeks.5）用于祈使句，表示祝愿。用于祈使句，表示祝愿。May you succeed!May you have a nice trip!
