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情态动词情态动词 情态动词表示说话人的语气和情态，需要，情态动词表示说话人的语气和情态，需要，可能，愿意和怀疑等。可能，愿意和怀疑等。 情态动词有一定的词义，但不完整，必须情态动词有一定的词义，但不完整，必须和主要动词的原形一起构成谓语。和主要动词的原形一起构成谓语。 情态动词情态动词 情态动词特点：情态动词特点： 1. 没有人称和数的变化没有人称和数的变化2. 情态动词情态动词+动词原形动词原形 情态动词情态动词 常用的情态动词有：常用的情态动词有：can, could, may, must, need,have to, ought to, be able to，shall, will, should, would, dare, might, 一一. can , could, be able to I. 1) can 表示体力或脑力方面的能力，或根据客观条件能够做表示体力或脑力方面的能力，或根据客观条件能够做某事的能力。某事的能力。 He can speak five languages. 2) 表示许可，在疑问句中表示要求，否定句中表示许可，在疑问句中表示要求，否定句中 表示不许。表示不许。 Can (May) I come in ? - Can I use your dictionary? - Of course, you can. This kind of thing cant go on. 3) 表示可能性，常用于疑问句和否定句中，指表示可能性，常用于疑问句和否定句中，指“某事是否是事某事是否是事实实”。 Can it be true? Can the hall seat a thousand people? She cant be here. Mary cant have gone there alone.4) 表示温和的命令或批评表示温和的命令或批评 You can go and fetch some water. You could read more in future. 5) be able to与与can 的比较的比较A) 表示能力时可通用表示能力时可通用 No one can / is able to do it. Can you come tonight? /Will you be able to come tonight?B) be able to可用于任何时态，可用于任何时态， can只能用在现在时或只能用在现在时或过去时（过去时（ could ）中。）中。 Im sorry I havent been able to answer your letter. He said he would be able to come home for Christmas.C) 表示经过努而成功地办到了某个具体的事情时，只能表示经过努而成功地办到了某个具体的事情时，只能用用be able to 不可用不可用 can。 With the help of the firemen, they were able to leave the burning house.2. could 1) could 是是can的过去时，除具有的过去时，除具有can的各种功能外，的各种功能外，还可以用来比较委婉，客气地提出问题或陈述看法。还可以用来比较委婉，客气地提出问题或陈述看法。 Could you come a little earlier? - Could I borrow your bicycle? - Yes, of course, you can. ( 不可用不可用could ) I could come earlier, if necessary.2) can 和和could 还可表示某人或某物一时的特点，可译还可表示某人或某物一时的特点，可译为为“有可能，有时会有可能，有时会”。 He can be very friendly. He could be very proud.二二. may, might 1） 表示许可，允许，译为表示许可，允许，译为“可以可以”（正式场合）（正式场合） You may take the book home. People may not pick flowers in the park. Id like to ask a question if I may ask. - May I watch TV tonight? -Yes, you may. (No, you mustnt/youd better not.) - May I smoke here? - Yes, please. / please dont.2) 表示推测，表示推测，“或许，可能或许，可能” 表示一件事或许会发生，表示一件事或许会发生，一般用在陈述句中。一般用在陈述句中。 It may rain tomorrow. They may not be there today. Fools may ask questions more than wise men can answer. Anybody may get ill.注：注：may 指指事实事实上的可能性上的可能性, can 指指逻辑逻辑上的可能性上的可能性Mr. Smith looks pale. He may be ill.Mr. Smith is in poor health. He can be ill at any time.3) 表示祝愿表示祝愿 May our friendship live long! May you succeed! May you have a good time! May you be happy!4) 常用在目的状语从句或让步状语从句中常用在目的状语从句或让步状语从句中 Get up early so that we may catch the first bus. She went by air that she might /could arrive earlier. Whoever he may be, he should obey the rules. He would work hard, however rich he might be.5）may well + 动词原形意为动词原形意为“理应，有足够的理由理应，有足够的理由” may /might as well+ 动词原形用来建议或劝说某人采动词原形用来建议或劝说某人采取某种行动，有时相当于取某种行动，有时相当于had better常译为常译为 “还不如还不如,不妨不妨”。 He may well be proud of his son. （他大可以他的儿子为荣）（他大可以他的儿子为荣） She may well say so. （她说得对）（她说得对） It is very late, so you may / might as well go to bed. Might: might是是 may 的过去式，在表示可能时可以换用，但的过去式，在表示可能时可以换用，但might 可能性较小，或表示更婉转的语气。可能性较小，或表示更婉转的语气。 Jim may lend you money. Jim might lend you money. Might I ask a question? Might I ask for a photo of your baby? I wonder if I might borrow some money?三三. must, have to, need1. must 的用法：的用法： 1） 表示必须要做的事，意为表示必须要做的事，意为“必须必须” ，否定式表示不应该，不，否定式表示不应该，不许可禁止等。在回答许可禁止等。在回答must的问句时的问句时,不用不用mustnt,而用而用neednt或或dont have to I must leave at 9. We must do everything step by step. We mustnt waste our time. I felt I must call and see him. - Must we hand in our exercises today? - Yes, you must. / No, you neednt. / No, you dont have to.2) must表示表示“偏要，偏偏偏要，偏偏”，或，或“（干吗）硬要（多指不愉快的（干吗）硬要（多指不愉快的事）事） Why must you always interrupt me? Must you go so soon? The car must break down just when we were about to start off. After I give her advice, she must go and do the opposite.3) must也可表示客观必然性，意为也可表示客观必然性，意为“必然会，总是会必然会，总是会” 。 All men must die. Truth must be out. Winter must be followed by spring 3) must 还可表示一种推断和揣测。还可表示一种推断和揣测。must +be对现在事实的猜对现在事实的猜测测;must +have done 对过去事实的猜测对过去事实的猜测. This must be Jims pen. You must be joking. I cant find my key. I must have left it in the bus. The book must have been written by a woman. You must have been thinking of something.2. must与与 have to的比较：的比较： 1). have to比较强调客观需要，表示因客观环境或事比较强调客观需要，表示因客观环境或事态促使而不得不做某事；态促使而不得不做某事；must强调主观看法，表示主强调主观看法，表示主观上认为有必要做某事。观上认为有必要做某事。 I must learn another foreign language. You have to learn another foreign language if you want to work here. You must be back before 10 oclock. You have to be back before 10 oclock because the train is to leave at 10: 15.2) have to多表示义务或习惯动作；多表示义务或习惯动作； must 则表示一种则表示一种重要或急迫的事情。重要或急迫的事情。 You have to care for the young. She has to be at the office before eight every day. You must go to the manager at once, or youll be dismissed. 3） have to可用于不同时态，可同其他情态动词可用于不同时态，可同其他情态动词 连用，而连用，而must则只有一种形式则只有一种形式. We will have to buy another TV set. She is always having to make decisions. He has had to reconsider his position. She may have to stay there longer. I have to /must leave now.3. need 的用法：的用法： 1）作情态动词用时，多用于疑问或否定句中。回答）作情态动词用时，多用于疑问或否定句中。回答need提出的提出的问句时，肯定常用问句时，肯定常用must否定常用否定常用neednt / dont have to You need not do anything here. He never need know. She need hardly say anything to him. I dont think he need come. Need I repeat it? There need be no hurry, need there? - Need I go so soon? - Yes, you must. / No, you neednt. / No, you dont have to. 2) need作情态动词用时，也常用在作情态动词用时，也常用在if，或，或unless 引导的条件状语从句或引导的条件状语从句或wonder后面的宾语从句。后面的宾语从句。 If I need start early, I will. I wonder whether I need advise him. I wont write to her unless I need write to her.3）need have +过去分词，表示不必做谋事，但过去分词，表示不必做谋事，但 却做了却做了,有责备之意有责备之意;didnt need / have to do表表 示不必做且没做示不必做且没做 You neednt have told them about it.I invited only two guests, so you neednt havebrought so much food.I didnt have to / didnt need to get up early on Sunday, so I stayed in bed until 8 oclock.need用做行为动词时的用法：用做行为动词时的用法：1) need to do ; need doing ; need to be done 的用法的用法I need to buy a new dictionary. My bike needs to be repaired / repairing.2) 在在will或或 shall 表示的将来时中表示的将来时中need常用常用做行为动词。做行为动词。You will never need to worry about him. You will need to say nothing 四四. will 和和 would 的用法：的用法：1. 表示意愿意志和决心或固执，用于非人主语时，表示表示意愿意志和决心或固执，用于非人主语时，表示固有性质，倾向固有性质，倾向 He is the man who will go his own way.Ill never play a joke on him. I wont argue with you.2. 表示客观事实表示客观事实 Fish will die out of water. Oil will float on water.3. 表示一种揣想，用于二，三人称表示一种揣想，用于二，三人称 It will be Mr. Wang knocking at the door. You will not be familiar with these rare plants.4. 用于疑问句表示邀请或请求用于疑问句表示邀请或请求 Will you give me a piece of paper? Wont you come in and have a little wine? Would you please tell me your telephone number?5. 表示表示“诺言诺言” ，“命令命令” ，“叮嘱叮嘱” ，“强迫强迫” 译译为为“保证保证/ 保证不，保证不， 必须，一定要必须，一定要 We will pay back the money soon. I wont do it any more, I promise you. Youll wait here till I come back. No one will leave the examination room before 12 oclock.6. 表示意图或允诺表示意图或允诺 You will have your share. I will trouble you for the dictionary.7. 表示拒绝，用表示拒绝，用wont I wont listen to your nonsense. The dog wont stop barking.8. would与与 will的用法基本相同，的用法基本相同，would是是will的过去式。的过去式。如：如：will表示习惯而表示习惯而would过去习惯；用在疑问句中过去习惯；用在疑问句中would比比will语气更温婉等差异。语气更温婉等差异。 I told him that I would go along with him. Im afraid the journey would be too expensive. Would like something to eat? When I was a child, I would go swimming every summer.五五. shall, should, ought 的用法的用法 A) shall的用法的用法1. 用于一，三人称，用于一，三人称， 表示征求意见或请求指示。表示征求意见或请求指示。 Shall I turn on the light? Shall we meet in the evening? Shall I come in？（你要我进来吗？）？（你要我进来吗？） May / Can / Might I come in?（我可以进来吗）（我可以进来吗） Shall they come in or wait outside? Shall he come to see you? Shall + he /she / they +do sth = Do you want him / her / them to do sth2. 用于二，三人称，表示决心，意志，允诺，命令，用于二，三人称，表示决心，意志，允诺，命令， 警告，威胁，命运或必然的结果等。警告，威胁，命运或必然的结果等。 You shall have my answer tomorrow.（允诺）（允诺） You shall be sorry for it one day. （ 警告）警告） You shall leave the room or Ill shoot. （ 警告）警告） They shall do as I tell them. （ 命令或吩咐）命令或吩咐） Nothing shall stop us from carrying out this plan. You shall not smoke here. （命令或禁止）（命令或禁止） Death is certain to all; all shall die. 死必临万物；万物皆会死死必临万物；万物皆会死 （命运）（命运） Who touches pitch shall be defiled. 玩火者必自焚玩火者必自焚 （必然结果）（必然结果）B) should的用法的用法1. 表示劝告，建议，应该做，且有一种道义上的责任。表示劝告，建议，应该做，且有一种道义上的责任。 You should study the article carefully. Such a thing shouldnt be allowed to happen again. I should help him because he is in trouble now. You should do it because you have promised to.2. 表示对现在，将来，过去情况的某种推测，译为表示对现在，将来，过去情况的某种推测，译为 “可能，应该，该可能，应该，该”。 He should arrive at noon. Jim should be at home now. They should have finished the work by tomorrow. They should have reached the town by now.3. 用于委婉，谦虚的提出意见，请求建议。用于委婉，谦虚的提出意见，请求建议。 I should say it would be better to try it again. I should think you are right. Id like to have a talk with you. 4. 用于疑问或感叹句中，表示意外，惊异等情绪，与用于疑问或感叹句中，表示意外，惊异等情绪，与what, how, why, who连用，且问句不需回答，有些相当于修辞性问句。连用，且问句不需回答，有些相当于修辞性问句。 Why should I fear? (=I dont fear at all.) What should I see but misery? = I could see nothing but misery.) Should we stand by and do nothing? Should you be so silly?5. 在某些从句中，表示惊异，不以为然等情绪。可译为在某些从句中，表示惊异，不以为然等情绪。可译为“竟然竟然” ；用在独立的；用在独立的that从句中，这时，从句中，这时，that从句已从句已成为感叹句，可视为省略了成为感叹句，可视为省略了Im sorry等；用在结果状语等；用在结果状语从句中，表示从句中，表示“竟会竟会” That things should come to this! 竟落到这种地步！竟落到这种地步！ That a man should be cruel! 人竟会如此残忍！人竟会如此残忍！ What have I said that you should get angry? 我说了什么竟使你生气了？我说了什么竟使你生气了？ It seems so unfair that this should happen to me. It wasnt right that such near neighbors should not know one another.6. 用来表示虚拟（用来表示虚拟（should + do / should + have done） 1）句中有表示命令，请求，建议，坚持等意义时，）句中有表示命令，请求，建议，坚持等意义时， 名词性从句中的谓语动词要用虚拟名词性从句中的谓语动词要用虚拟(should + do) The teacher suggested that we should practice speaking English as much as possible. My suggestion is that you should go with us. It is suggested that we should start work at once.He made a suggestion that we should help the poor.2）在下面结构的主语从句中）在下面结构的主语从句中 It is important / necessary / natural / strange / a pity etc用虚拟用虚拟 (should + do) It is important that we should study another foreign language. It is a great pity that she should have failed to see such a wonderful performance.3) 在在 in case引起的状语从句中，引起的状语从句中， 谓语动词用谓语动词用(should + do) Be quiet in case you should wake the baby.4) should + have done表示过去应该做某事却没做。表示过去应该做某事却没做。含有含有“责备，内疚责备，内疚”之意。之意。 She should have helped you a lot. You should have told him about it. They should / ought to have come back yesterday.六六. 情态动词情态动词+动词完成式的用法动词完成式的用法1. may和和might +动词完成式动词完成式 1）常用于推测过去的行为，表示）常用于推测过去的行为，表示“可能已经可能已经” He may have received the letter. It might have happened last October. 2）也可表示将来某时之前的情况）也可表示将来某时之前的情况 He may have left when you get there. She might have died before he returns. 3）表示现在已经完成的情况）表示现在已经完成的情况 He might have arrived now. She may have got up now.2. can / could +动词完成式动词完成式 1) 表示本来能做而没做的事，有一种对过去未付表示本来能做而没做的事，有一种对过去未付 朱实施的事情的惋惜朱实施的事情的惋惜 I could have passed the exam, but I was too careless. In that case we could have done it better. 2）对过去某种事实或行为的推测）对过去某种事实或行为的推测 Where can / could she have gone?3. must +动词完成式动词完成式, 表示对过去行为的推断，具表示对过去行为的推断，具 有较大的可能性，译为有较大的可能性，译为“一定，想必一定，想必” She must have gone through a lot. 她一定吃了不少苦她一定吃了不少苦 He must have known about it.4. neednt +动词完成式和动词完成式和 didnt need to do 1）neednt +动词完成式动词完成式,表示一种已经做过的但并无比要的行为表示一种已经做过的但并无比要的行为 You neednt have watered the flowers, for it is going to rain. 2）didnt need to do, 表示没有必要做某事，实际上也没做。表示没有必要做某事，实际上也没做。 I didnt need to clean the windows. My sister did it.七七. dare的用法的用法1）dare 用作情态动词常表示现在或将来时间，有时也用作情态动词常表示现在或将来时间，有时也可表示过去，可用于肯定句，否定句，疑问句或可表示过去，可用于肯定句，否定句，疑问句或if,unless等引导的从句等引导的从句 He dare go deep into the mountains alone. She dare not say what she thinks. She never dare speak in public. No one dare go there. How dare you do such a thing? Dare you go home alone? I wonder if she dare come home. I wonder whether she dare disclose the secret.2) dare 用作行为动词时常用作及物动词，表示用作行为动词时常用作及物动词，表示“敢于，敢于，敢冒，敢于面对，向敢冒，敢于面对，向挑战挑战”后可跟名词，代词或不后可跟名词，代词或不定式定式 He dares any difficulties. He dares me to jump over the wall. 他向我挑战跳过那堵墙他向我挑战跳过那堵墙 I dare you to do it. 量你也不敢量你也不敢 He dared to swim in the river. She didnt dare to tell her mother about it. 注：注：Dare同同 shall, will, should, would, have, had等连等连用时，常用作行为动词用时，常用作行为动词. I will not dare to climb the tree. He would never dare to do it. They have never dared to swim in the lake.八八. 情态动词情态动词+动词进行式该结构表示动词进行式该结构表示“应当正在应当正在可能正在可能正在” What can / could she be doing now? She may / might be watering the flowers. She must be watering the flowers. She cant be watering the flowers. She should / ought to be watering the flowers.九九. 1) used to + V. ( usednt to + V. / didnt use to + V. Used + S + to + V. / did + S + use to + V.) 2) had better / best (not) +V.(Had +S +better +V.) 3) would rather ( not ) +V. You had better not go by air. What had we better do? Hadnt we better leave now? Had we better not leave now? Better say yes, if he asks you. Wouldnt you rather work here? I would rather have come back yesterday afternoon.
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