情态动词(初中版

1、什么是助动词 协助主要动词构成谓语动词词组的词叫助动词（Auxiliary Verb）。被协助的动词称作主要动词（Main Verb）。助动词自身没有词义，不可单独使用。 助动词(auxiliary)主要有两类：基本助动词(primary auxiliary)和情态助动词(modal auxiliary)。基本助动词有三个：do, have和be；情态助动词有十三个：may, might; can, could; will, would; shall, should; must, need, dare, used to, ought to. 上述两类助动词的共同特征是，在协助主动词构成限定动词

2、词组时，具有作用词的功能： 助动词be的用法 1） be +现在分词，构成进行时态，例如：They are having a meeting.他们正在开会。English is becoming more and more important. 英语现在越来越重要。2)be + 过去分词，构成被动语态，例如：The window was broken by Tom.窗户是汤姆打碎的。English is taught throughout the world.世界各地都教英语。3） be + 动词不定式，可表示下列内容：表示最近、未来的计划或安排，例如： He is to go to New

3、York next week.他下周要去纽约。 We are to teach the fresh persons.我们要教新生。说明： 这种用法也可以说成是一种将来时态表达法。 助动词have的用法 1）have +过去分词，构成完成时态，例如：He has left for London.他已去了伦敦。By the end of last month, they had finished half of their work.2）have + been +现在分词，构成完成进行时，例如：I have been studying English for ten years.3）have+be

4、en +过去分词，构成完成式被动语态，例如：English has been taught in China for many years. 助动词do 的用法 1） 构成一般疑问句，例如：Do you want to pass the CET? 你想通过大学英语测试吗？Did you study German? 你们学过德语吗？2） do + not 构成否定句，例如：I do not want to be criticized.我不想挨批评。He doesnt like to study.他不想学习。In the past, many students did not know the i

5、mportance of English.3)构成否定祈使句，例如：Dont go there.不要去那里。Dont be so absent-minded.不要这么心不在焉。说明： 构成否定祈使句只用do，不用did和does。4） 放在动词原形前，加强该动词的语气，例如：Do come to my birthday party.一定来参加我的生日宴会。I did go there.我确实去那儿了。I do miss you.我确实想你。5） 用于倒装句，例如：Never did I hear of such a thing.我从未听说过这样的事情。Only when we begin ou

6、r college life do we realize the importance of English.只有在开始大学生活时我们才认识到英语的重要性。说明： 引导此类倒装句的副词有never, seldom, rarely, little, only, so, well等。6） 用作代动词，例如：- Do you like Beijing?-你喜欢北京吗？- Yes, I do.-是的，喜欢。（do用作代动词，代替like Beijing.）He knows how to drive a car, doesnt he?情态助动词的意义和用法情态助动词从最普通的意义上来说，是修饰分句意义的

7、一种方式，它可以反映说话者对其表述是否真实和可能的程度作出判断。但不同的情态助动词本身所包含的意义和用法又不同，下面逐个分析。 can和could的用法l 表示能力或客观可能性，还可以表示请求和允许。如：Can you finish this work tonight?Man cannot live without air.注意：could也可表示请求，预期委婉，主要用于疑问句，不可用于肯定句，答语应用can（即could不能用于现在时态的简略答语中）。如： Could I come to see you tomorrow? Yes, you can. （否定答语可用No, Im afraid

8、 not.） can表示能力时，还可用be able to代替。如： Ill not be able to come this afternoon.l 表示惊异、怀疑、不相信的态度。（主要用在否定句、疑问句或惊叹句中）Can this be true? How can you be so careless! This cannot be done by him.l “can(could) + have + 过去分词”的疑问或否定形式表示对过去发生的行为怀疑或不肯定。如：He cannot have been to that town. may和might的用法l 表示许可。表示请求、允许时，m

9、ight比may的语气更委婉一些，否定回答时要用mustnt表示“不可以”、“禁止”、“阻止”之意。如：You may drive the car. Might I use your pen? No, you mustnt.l 用May I . 征询对方许可在文体上比较正式，在口气上比较客气。在日常口语中，用Can I . 征询对方意见在现代口语中更为常见。l 用于祈使句中表示祝愿。如：May you succeed!l 表示推测、可能（疑问句不能用于此意）。如：He may be very busy now.l “may(might) + have + 过去分词”表示对过去发生的行为的推测。

10、如：He may not have finished the work. must和have to的用法l 表示必须、必要。如：You must come in time.回答must引出的问句时，如果是否定的回答，不能用mustnt，而要用neednt或dont have to。Must we hand in our exercise books today?Yes, you must. (No, you dont have to.)l “must be + 表语”的结构表示推测，它的否定或疑问式用can代替must。This must be your pen.l “must + have

11、+ 过去分词”的结构常用在肯定句中，表示对过去发生的行为的推测。它的否定或疑问式用can代替must。He must have been to Shanghai.l have to的含义与must相似，两者往往可以互换使用，但have to有各种形式，随have的变化而定。must与have to有下列几点不同：i. must表示的是说话人的主观看法，而have to则往往强调客观需要。如：The play is not interesting. I really must go now.I had to work when I was your age.ii. must一般只表现在，have

12、则有更多的时态形式。iii. 二者的否定意义不大相同。如：You mustnt go. 你可不要去。You dont have to go. 你不必去。iv. 询问对方的意愿时应用must。如：Must I clean all the room? dare和need的用法l need表示“需要”或“必须”，作情态动词时，仅用于否定句或疑问句中，在肯定句中一般用must, have to, ought to,或should代替。如：You neednt come so early.Need I finish the work today?Yes, you must.l 注意：neednt + 不

13、定式的完成式“表示本来不必做某事而实际上做了某事”。如：You neednt have waited for me.l Dare作情态动词时，主要用于疑问句、否定句和条件从句中，一般不用在肯定句中。如：How dare you say Im unfair？He darent speak English before such a crowd, dare he?l Dare和need常用作实义动词，有时态、人称和数的变化，所不同的是，作实义动词时，在肯定句中，dare后面通常接带to的不定式，在否定和疑问句中，dare后面可接带to或不带to的不定式。如：I dare to swim acros

14、s this river.He does not dare (to) answer.I wondered he dare (to) say that.He needs to finish it this evening. shall和should的用法l Shall用于第一人称，表示征求对方的意愿。如：What shall we do this evening?l Shall用于第一、第三人称疑问句中，表示说话人征求对方的意见或向对方请示。如：Shall we begin our lesson?When shall he be able to leave the hospital?l Shal

15、l用于第二、第三人称，表示说话人给对方命令、警告、允诺或威胁。如：You shall fail if you dont work harder. （警告）He shall have the book when I finish reading. （允诺）He shall be punished. （威胁）l Should表示劝告、建议、命令，其同义词是ought to；在疑问句中，通常用should代替ought to。如：You should go to class right away.Should I open the window?Should的含义较多，用法较活，请看下面的句子： I

16、 should think it would be better to try it again. 我倒是认为最好再试一试。 You are mistaken, I should say. 依我看，你是搞错了。 I should advise you not to do that. 我倒是劝你别这样做。 This is something I should have liked to ask you. 这是我本来想问你的。从以上例句可以看出：情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。Should还可以用在if引导的条件从句，表示一件事听起来可能性很小，但也不

17、是完全没有可能。相当于“万一”的意思。从句谓语由should加动词原形构成，主句谓语却不一定用虚拟语气。如： Ask her to ring me up if you should see her. 你万一见到她，请让她给我打个电话。 If you should change your mind, please let us know. 万一你改变主意，请通知我们。 Should I (If I should) be free tomorrow I will come. 万一我明天有时间，我就来。此外，Why(or How) + should结构表示说话人对某事不能理解，感到意外、惊异等意思。

18、意为“竟会”。如： Why should you be so late today? 你几天怎么来得这么晚？ Where is Betty living? 贝蒂住在哪里？ How should I know? 我怎么会知道呢？ I dont know why you should think that I did it. 我真不知道你凭什么认为这件事是我干的。l “should + have + 过去分词”结构一般表示义务，表示应该做到而实际上没有做到，并包含一种埋怨、责备的口气。如：She should have finished it. will和would的用法l 表示请求、建议等，wo

19、uld比will委婉客气。如：Would you pass me the book?l 表示意志、愿望和决心。如：I will never do that again.They asked if we would do that again.l 用“will be”和“will(would) + have + 过去分词”的结构表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。如：This will be the book you want.He will have arrived by now.The guests would have arriv

20、ed by that time.I thought you would have finished this by now.l Would可表示过去反复发生的动作或某中倾向。Would表过去习惯时比used to正式，并没有“现已无此习惯”的含义。如：The wound would not heal.During the vacation he would visit me every week.l 表料想或猜想。如：It would be about ten when he left home.What would she be doing there?I thought he would

21、have told you all about it. ought to的用法l Ought to表示应该。如：You ought to take care of him.l 表示推测。注意与must表示推测时的区别：He must be at home by now. （断定他已到家）He ought to be home by now. （不十分肯定）This is where the oil must be. （比较直率）This is where the oil ought to be. （比较含蓄）l “ought to + have + 过去分词”表示过去应做某事而实际未做。如：Y

22、ou ought to have asked him (but you didnt).这时，ought to和should可以互相换用。 used to，had better，would rather的用法l Used to表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变。如：He told us he used to play football when he was young.在疑问句、否定句、否定疑问句或强调句中，可有两种形式：疑问句Did you use to go to the same school as your brother?Used you to go

23、to the same school as your brother?否定句I usednt to go there.I didnt use to go there.used nt 亦可拼作usednt，但发音皆为ju:znt。否定疑问句Usednt you to be interested in the theatre?Didnt you use to be interested in the theatre?强调句I certainly used to smoke, but it was a long time ago.I certainly did use to smoke, but i

24、t was a long time ago.其反意疑问句或简略回答中，也有两种形式：She used to be very fat, didnt she? （正式）/ use(d)nt she? （口语）Did you use to play chess? Yes, I did.Used you to get up early in the morning? Yes, I did. (Yes, I used to.) Had better意为“最好”，后接不带to的不定式。如：We had better go now.Yes, we had (wed better / we had bette

25、r).Hadnt we better stop now? (Had we better not stop now?)I think Id better be going. （用于进行时态，表“最好立即”）You had better have done that. （用于完成时态，表未完成动作。注：had best与had better同意，但较少用。You had better 用于同辈或小辈，对长辈不可用。 Would rather意为“宁愿”，表选择，后接不带to的不定式。如：Would you rather work on a farm?Wouldnt you rather stay

26、here?No, I would not. Id rather go there. 由于would rather表选择，因而后可接than。如：I would rather work on a farm than in a factory.I would rather watch TV than go to see the film.I would rather lose a dozen cherry trees than that you should tell me one lie.Id rather you didnt talk about this to anyone. （句中的d r

27、ather不是情态动词，would在此是表愿望的实义动词） need和dare的用法need和dare既可用作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句和疑问句。用作实义动词时，可用于各种句式。1.用作情态动词-Need I come? -Yes, you must. -我需要来吗？ -需要。You neednt telephone him now. 你现在不必打电话给他。I dont think you need worry. 我想你不必发愁。She dare not go out alone at night. 她晚上不敢一个人出去。How dare you say Im

28、unfair? 你竟敢说我不公平？2. 用作实义动词You dont need to do it yourself. 你不必亲自做这件事。We need to tell them the news. 我们需要把这消息告诉他们。The table needs painting (to be painted.). 桌子需要油漆一下。We should dare to give our own opinion. 我们要敢于提出自己的观点。He did not dare (to) look up. 他不敢抬头看。I dare day hell come again. 我想他会再来的。（I dare s

29、ay为固定习语） 情态动词后跟完成式和进行式的用法1.情态动词后跟完成式，表“应当已经”，“想必已经”，“本来可以”等意。I should have finished the work earlier. 我应当早一点完成这项工作的。He isnt here. He must have missed the train. 他还未到，一定是没赶上火车。Where can (could) he have gone? 他能到那里去了呢？You may (might) have read about it. 你可能在报上已经读到这件事了。You could (might) have been more

30、careful. 你本来可以更细心的。He neednt have worried about it. 他本不必为此事担心。There was a lot of fun at yesterdays party. You ought to have come, but why didnt you? 昨天的聚会非常有意思。你本应该来，为何不来呢？2. 情态动词后跟进行式，表示“想必正在”，“可能正在”，“应当正在”等意。Its twelve oclock. They must be having lunch. 现在是十二点。他们一定正在吃饭。They may be discussing this

31、problem. 他们可能正在论讨这个问题。He cant be telling the truth. 他说的不可能是真话。She shouldnt be working like that. Shes still so weak. 她不应当那样干，她身体仍那么虚。情态动词表推测的用法小结（一）情态动词表推测的三种句式 1.在肯定句中一般用must (一定)，may（可能），might / could（也许，或许）。（1）He must/may/might know the answer to this question? 他一定/可能/也许知道这个问题的答案。 （2）It is cold i

32、n the room. They must have turned off the heating. 屋里很冷，他们肯定把暖气关了。 2.否定句中用cant / couldnt(不可能), may not/might not(可能不)。 （1）It cant/couldnt be the headmaster. He has gone to America. 这不可能是校长，他去美国了。 （2） He may not/might not know the scientist. 他也许不认识那位科学家。 3.疑问句中用can/could (能?)。 （1）Could he have finish

33、ed the task? 他可能把任务完成了吗？ （2）Can he be at home now? 他现在能在家吗？ 注：以上三种句式中情态动词的语气按程度都是依次递减的。Might, could并非may, can的过去式，而表示语气较为委婉或可能性较小。 （二）情态动词表推测的三种时态 1.对将来情况的推测，用“情态动词 + 动词原形”。 （1）She must / may / might / could arrive before 5. 5:00前她一定/可能/也许到。 （2）She must/may/might/could walk miles and miles among the

34、 hills without meeting anyone. 她一定/可能/也许会在山里一连走好几英里而遇不到一个人。 2.对现在或一般情况的推测，用“情态动词 + be”，“情态动词 +be doing”或“情态动词 + 动词原形”。 （1）He must / may / might / could be listening to the radio now. 他一定/可能/也许正在听收音机。 （2）He cant ( couldnt ) / may ( might ) not be at home at this time. 这个时候他不可能/可能不在家。 （2） Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ? 3.对过去情况的推测，用“情态动词 + have +过去分词”。 （1）It must / may / might / could have rained last night .The ground is wet. 地湿了，昨晚肯定/可能/也许下雨了。 （2）The door was locked. He can ( could ) not / may ( migh