情态动词的用法总结.doc

情态动词的用法总结2 情态动词表示可能、必要、允许、愿望、猜测等意义，它们本身虽有一定词义，但不能独立用作谓语、也没有人称和数的区别，其后必有动词原形，共同构成复合谓语。 possibility: can / could, may / might certainty: must, will, should ability: can / could, be able to permission: can / could, may / mightrequests: can / could, will / would suggestions: could / may /might, shallnecessity: must, have to, have got to, need advice: ought to, had better语法特征1. 情态动词没有人称和数的变化,即情态动词第三人称单数不加- s (have to, have got to, be able to 除外)。2. 情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生。3. 情态动词本身具有一定词义,但不能单独做谓语, 后一般接动词原形一起构成谓语部分 (ought to, have to/have got to, be able to除外)。4. 情态动词无非谓语形式,即无不定式、分词等形式。1. can和be able to1) can (could) 表示能力、可能, 只用于现在式和过去式can表能力时意味着凭体力或脑力或技术等可以做。I can climb this pole. He is only four , but he can read. Fire cant destroy gold. 因为can不能和其他助动词连用，所以表示将来式时用will be able to ：You will be able to skate after practising it times.2)表可能性 Can the news be true? It cant be true. What can he possibly mean? 3)表示允许（和may意思相近）常见于口语。Can (May) I come in ? 我能进来吗？Can I smoke here ? could表过去的能力、可能和许可，（间引） At that time we thought the story could not be true.4) be able to可以用于各种时态。只用be able to的情况：a. 位于助动词后。b. 情态动词后。c. 表示过去某时刻动作时。d. 用于句首表示条件。 e. 表示成功地做了某事时,只能用was/ were able to,不能用could。注意:could不表示时态,只表示：1) 提出委婉的请求,回答中不可用could。 - Could I have the television on? - Yes, you can. / No, you cant.2) 在否定、疑问句中表示推测或怀疑。 He couldnt be a bad man.2. may和might 1) 表示允许或请求;表示没有把握的推测;may 放在句首,表示祝愿。May God bless you! He might be at home.注: might 表示推测时,不表示时态。只是可能性比may 小。2)当回答由may 引起的问题时，否定答语要用must not,表示不许可、不应该、不行。May I come in? ( = can ) Yes, you may. No, you mustnt. 3)表建议（可和as well 连用）成语:may/ might as well,后面接不带to 的不定式 意为不妨e.g. If that is the case, we may as well try. You may as well stay where you are.might 1)表过去的可能和允许多用于间接引语 She said that he might take her dictionary.除在间接引语中外，might一般不表示过去的可能与许可。表过去的可能可用could，表过去的许可可用were (was) allowed to。 2)表现在的可能，其可能性要比may小。Electric irons could be dangerous; they might give you a severe shock.3. have to和must1) 两词都是必须的意思, have to 表示客观的需要, must 表示说话人主观上的看法, 即主观上的必要。e.g. My brother was very ill, so I had to call the doctor in the middle of the night. 1、must 的主要用法。1)表示必须、必要 We must do everything step by step .2)must 的否定式有两个：当回答由must引起的问题时，否定答复要用neednt或dont have to 表 不必、无须、用不着、不一定的意义。当表示不应该、不许可、禁止时，就用must not。Must I go tomorrow? 明天我必须去吗？ Yes, please.是的，请吧！ No , you neednt.( = dont have to ) 不，你不必去。 You must not smoke here. 你不准在这儿吸烟.have to的含义与must是很接近的,只是have to 比较强调客观需要，must着重说明主观看法。I must clean the room.（主观想法）Its getting late. I have to leave now.（客观需要）另外，have to 能用于更多时态：We had to be there at ten . We will have to reconsider the whole thing.have to 的否定式：dont have to do 不必做 。You dont have to go right now. 2) have to有人称、数、时态的变化,而must只有一种形式。但must可用于间接引语中表示过去的必要或义务。e.g. He had to look after his sister yesterday.3) 在否定结构中：dont have to 表示不必; mustnt表示禁止。You mustnt tell him about it.4. 情态动词ought to 的用法。Ought to 后接动词原形，表义务，但不及must 那样具有信心:You dont look well. You ought to go to the doctor.Ought to 用于否定句，可缩略为oughtnt to。You oughtnt to smoke so much. 也可以用于疑问句，如：Ought you to smoke so much?你应该抽这样多烟吗？Ought to 在间接引语中表过去时形式不变，如：He said you ought to tell the police.5. 情态动词shall与should 的用法 1、shall的用法 1)用于第一人称征求对方的意见，如：What shall I wear on the journey? Shall we dance? 2)shall 用于第二、三人称时表允诺，She shall get her share. You shall have it back tomorrow.情态动词should一般不应被认为是情态动词shall的过去式，主要用法有：1)用于第一人称疑问句中询问对方的意愿，但语气较委婉温和，如：What should we do now? 2)表示应该、必须，常与must 换用。例如：We should (must) master a foreign language at least.3) 在It is natural (strange, necessary, surprised, impossible, important ) that句型中，在It is suggested / ordered / demanded that.句型中，主语从句中的谓语动词要用should +动词原形表示理所当然、奇怪、必要、惊异等的意思。在lest（以免）、for fear (that) (以防)、in case（以备万一）等之后也要用should+动词原形 如： It is strange that he should say so. 6. 情态动词will和would的用法 1）表示意志，决心或愿望。例如： He would not let me try it . 2）will表示经常性、习惯性、倾向性，would表示过去的习惯行为。(必须与行为动词连用，would= used to) 例如：He will sit there hour after hour looking at the traffic go by.3）用于第二人称作主语的疑问句中，表示对对方的请求，would的语气比will委碗:Would/Will you kindly tell me the way to the station? 7. 情态动词need和dare的用法 这两个词只能算半情态动词，它们作情态动词用时，一般用在否定句和疑问句中，如果用在肯定句中，多数是实义动词，一般现在时单数第三人称就要加s，并有时态变化，后接不定式时须带to, 试比较：Need I explain once more? （情态）The question needs to be discussed. （实义）She dare not tell the truth to him. （情态）We should dare to think, to speak and to act.（实义）She doesnt dare to go out at night by herself.（实义She dare not go out at night by herself.（情态）8. should和ought to should 和ought to 都为应该的意思,可用于各种人称。e.g. - Ought he to go? - Yes. I think he ought to.表示要求,命令时,语气由 should(应该)、(had better最好)、must(必须)渐强。9. had better表示最好 had better 相当于一个助动词,它只有一种形式,它后面要跟动词原形。had better (not) do e.g. It is pretty cold. Youd better put on my coat. had better have done表示与事实相反的结果,意为本来最好。You had better have come earlier.10. would rather表示宁愿 would rather (not) do would ratherthan宁愿而不愿 would sooner had rather had sooner表示宁愿、宁可的意思。e.g. If I have a choice, I had sooner not continue my studies at this school11. will和would 1) would like to do = want to 想要 e.g. Would you like to go with me?2) Will you? / Would you like? 表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。3) 否定结构中用will, 一般不用would, wont you是一种委婉语气。e.g. Wont you sit down?12. need和dare 这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都只能用于疑问句,否定句和条件句。need 作实义动词时后面的不定式必须带to,而dare作实义动词用时, 后面的to时常可以被省略。1) 实义动词: need+ n. / to do sth.2) 情态动词: need,只用原形need后加do,否定形式为need not. e.g. - Need you go yet? - Yes, I must. / No, I neednt.3) need, want, require, worth(形容词)后面接doing也可以表被动need doing = need to be done情态动词的推测用法从推测角度分：可 能(1-50%) might; may; could; 很可能(60-90%) should; ought to; would; will肯 定(100%) must 不 可 能(0%) cant-Theres someone at the door. Didnt you hear the bell? -It _ be Jack.从形式角度分一般式Model V. + be / do 进行式Model V. + be doing 完成式 Model V. + have doneHe should be back now. He must be watching the live football match. She may have arrived there.表示推测的用法 can, could, may, might, must 皆可表示推测,其用法如下：must表示推测 1) must用在肯定句中表示较有把握的推测,意为一定。2) must表对现在的状态或现在正发生的事情的推测时, 后面通常接系动词be的原形或行为动词的进行时。e.g. You have worked hard all day. You must be tired.（对现在情况推测判断)He must be working in his office. 他一定在办公室工作呢。比较: He must be staying there. 他现在肯定呆在那里。 He must stay there. 他必须呆在那。3) must 表示对已发生的事情的推测时, 要接完成时。 e.g. I didnt hear the phone. I must have been asleep.4) must表示对过去某时正发生的事情的推测, 后面要接不定式的完成进行时。-Why didnt you answer my phone call? -Well, I must have been sleeping, so I didnt hear it. 5) 否定推测用cant. e.g. If Tom didnt leave here until five oclock, he cant be home yet.1) 情态动词+动词原形,表示对现在或将来的情况的推测,此时动词通常为系动词。e.g. I dont know where she is, she may be in Wuhan.2) 情态动词+动词现在进行时, 表示对现在或将来正在进行的情况进行推测。e.g. At this moment, our teacher must be correcting our exam papers3) 情态动词+动词完成时, 表示对过去情况的推测。e.g. We would have finished this work by the end of next December. 4) 情态动词+动词的现在完成进行时, 表示对过去正在发生事情的推测。e.g. Your mother must have been looking for you. 5) 推测的否定形式,疑问形式用cant, couldnt表示。e.g. Mike cant have found his car, for he came to work by bus this morning.注: could, might表示推测时不表示时 态,其推测的程度不如can, may。6.情态动词+have+过去分词1) may (might) have + done sth., can (could) have + done sth. 表示过去,推测过去时间里可能发生的事情。e.g. Philip may (might) have been hurt seriously in the car accident.2) must have done sth., 表对过去时间里可能发生的事情的推测,语气较强,有肯定的意思。e.g. - Linda has gone to work, but her bicycle is still here. - She must have gone by bus.当情态动词表示推测时，其所在的句子的反意疑问句的简短问句应与情态动词后的主要动词的形式相呼应。Model V + be 是对现在所作推测，反意问句应作为一般现在时或现在进行时处理。He may be in the library, isnt he? (Im afraid )He is in the library, isnt he?They cant be playing on the playground, are they? (Im sure )They arent playing, are they?Model V. + have done 是对过去或人生经历所作推测， 反意问句应作为一般过去时或现在完成时处理。 如：You must have seen the film yesterday, didnt you? He cant have missed the train then, did he? She must have been to the Great Wall, hasnt she? They may have lived here for a long time, havent they?3) ought to have done sth.should have done sth.本应该做某事,而事实上并没有做; 否定句表示不该做某事而做了。 注: ought to 在语气上比should 要强。e.g. He ought not to have thrown the old clothes away.(事实上已扔了。)4) neednt have done sth. 本没必要做某事e.g. I dressed very warmly for the trip, but I neednt have done so. The weather was hot.5) would like to have done sth. 本打算做某事e.g. I would like to have read the article, but I was very busy then.情态动词的虚拟用法could have done 本来可以做 惋惜 might have done 本来也许可以 惋惜neednt have done 原本不必做 惋惜 should have done 本应该做 责备shouldnt have done 本不应该做 责备 ought to have done 本应该做 责备I could have passed my examination easily but I made too many stupid mistakes. If we had taken the other road, we might have arrived earlier. You neednt have watered the flowers, for its going to rain.They should not have left so soon. You ought not to have been so careless. 3) ought to have done sth.should have done sth.本应该做某事,而事实上并没有做; 否定句表示不该做某事而做了。注: ought to 在语气上比should 要强。He ought not to have thrown the old clothes away.(已扔了。) 4) neednt have done sth. 本没必要做某事e.g. I dressed very warmly for the trip, but I neednt have done so. The weather was hot.5) would like to have done sth. 本打算做某事 I would like to have read the article, but I was very busy then.2008全国各省市高考试卷中的情态动词真题01、(08全国卷II 17) Liza _ well not want to go on the trip - she hates traveling.A. will B. can C. must D. may02、(08上海春卷 27) When I was young, I was told that I _ play with matchesA. wouldnt B. neednt C. mustnt D. darent 03、(08上海卷29) According to the air traffic rules, you _ switch off your mobile phone before boarding.A. may B. can C. would D. should04、(08天津卷 06)She _ have left school, for her bike is still here. A. cant B. wouldnt C. shouldnt D. neednt05、(08重庆卷 30) -I cant find my purse anywhere. -You have lost it while shopping. A. may B. can C. should D. would06、(08辽宁卷 22)Peter _ be really difficult at times even though hes a nice person in general.A. shall B. should C. can D. must07、(08山东卷 24)Thank you for all your hard work last week. I dont think we _ i