1、 情态动词情态动词 概说：概说：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。情态动词有一定的词可能，愿意和怀疑等。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义，但不完整，必须和主要动词的原形一起构成谓语。常用的情态动词有：构成谓语。常用的情态动词有：can,could,may,might,must,have to,ought to,need,dare,shall,will,should,would,be able to,etc.v一一.can,could,be able tovI.1)can 表示体力或脑力方面的能力，或根据客表
2、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。观条件能够做某事的能力。v A blind man can not judge color.v He can speak five languages.v 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。v Can(May)I come in?v -Can I use your dictionary?v -Of course,you can.v 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“
3、某事是否是事实某事是否是事实”。vCan it be true?vCan the hall seat a thousand people?vSomeone is knocking at the door.Who can it be?vShe cant be here.He cant be serious.vMary 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v You can go and fetch some water.v You can clean the windows first.v You could read more in
4、 future.v You could be more careful.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vNo one can/is able to do it.vCan 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只能用在现在时或过只能用在现在时或过去时（去时（could）中。）中。vIm sorry I havent been able to answer your letter.vHe says/said he wil
5、l/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。vWith the help of the firemen,they were able to leave the burning house.vAfter years of hard work he was able to win the prize 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，还的各种功能外，还可以
6、用来比较委婉，客气地提出问题或陈述看法。可以用来比较委婉，客气地提出问题或陈述看法。vCould you come a little earlier?vIm sorry I couldnt lend you the book now.v-Could I borrow your bicycle?v-Yes,of course,you can.(不可用不可用could)v 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”。vHe can be ve
7、ry friendly.He could be very proud.vMan can be as cruel as wild beasts.vChildren could be very trying.(伤脑筋伤脑筋)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）vYou may take the book home.v People may not pick flowers in the park.v Id like to ask a question if I may ask.v-May I watch TV tonight?v
8、-Yes,you may.(No,you mustnt/youd better not.)v-May I smoke here?v-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。vIt may rain tomorrow.vThey may not be there today.vFools may ask questions more than wise men can answer.vAnybody may get ill.注：注：may 指指事实事实上的可能性
9、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v May our friendship live long!May you succeed!v 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vGet up early so that we may catch the first bus.v
10、She went by air that she might/could arrive earlier.vWhoever he may be,he should obey the rules.v 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”。vHe may well be p
11、roud of his son.v （他大可以他的儿子为荣）（他大可以他的儿子为荣）vShe may well say so.（她说得对）（她说得对）vIt is very late,so you may/might as well go to bed.vMight:might是是 may 的过去式，在表示可能时的过去式，在表示可能时可以换用，但可以换用，但might 可能性较小，或表示更婉转可能性较小，或表示更婉转的语气。的语气。vJim may lend you money.vJim might lend you money.vMight I ask a question?vMight I
12、 ask for a photo of your baby?vI 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，否定式表示不应该，不许可禁止等。在回答表示不应该，不许可禁止等。在回答must的问的问句时句时,不用不用mustnt,而用而用neednt或或dont have to v I must leave at 9.v We must do everything step by step.v We mustnt waste ou
13、r time.v I felt I must call and see him.v-Must we hand in our exercises today?v-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（干吗）硬要（多指不愉快的事）（多指不愉快的事）vWhy must you always interrupt me?vMust you go so soon?vThe car must break down just when we were about to start o
14、ff.vAfter 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，总必然会，总是会是会”。v All men must die.v Truth must be out.v 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+do对对现在事实的猜测现在事实的猜测;must+have done 对过去事实对过去事实的猜测的猜测.vThis must be Jims pen.vYou mus
15、t be joking.vI cant find my key.I must have left it in the bus.vThe book must have been written by a woman.vYou must have been thinking of something.2.must与与 have to的比较：的比较：v 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。vI must lea
16、rn another foreign language.vYou have to learn another foreign language if you want to work here.vYou must be back before 10 oclock.vYou 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 则表示一种重则表示一种重要或急迫的事情。要或急迫的事情。vYou have to care for the y
17、oung.vShe has to be at the office before eight every day.vYou 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.v We will have to buy another TV set.v She is always having to make decisions.v He has had to reconsider his positio
18、n.v She may have to stay there longer.v 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）作情态动词用时，多用于疑问或否定句中。回答答need提出的问句时，肯定常用提出的问句时，肯定常用must否定常用否定常用neednt/dont have tovYou need not do anything here.v He never need know.v She need hardly say anything to him.v I dont think he need come.
19、v Need I repeat it?v There need be no hurry,need there?v-Need I go so soon?v-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。v If I need start early,I will.v I wonder whether I need advise him.v I wont write to her
20、 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 un
21、til 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vI need to buy a new dictionary.vMy 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。vYou will never need to worry about him.vYou will need to say nothing 四四.will 和和 would 的用法：的
22、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She wont lend me the money.He is the man who will go his own way.Ill never play a joke on him.I wont argue with you.The window wont open.The door wont shut.2.表示客观事实表示客观事实vFish will die out of water.Oil will float on water.3.表示一种揣想，用于二，
23、三人称表示一种揣想，用于二，三人称vIt will be Mr.Wang knocking at the door.vShe will have heard of the accident.vSorry to be late.You will have been waiting for some time.vYou 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vWill you give me a piece of paper?vWont you come in and have a little
24、wine?vWould 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vWe will pay back the money soon.vI wont do it any more,I promise you.vYoull wait here till I come back.vNo one will leave the examination room before 12 voclock.vAll will arrive befor
25、e 7:45.vYou will finish it before you leave.6.表示意图或允诺表示意图或允诺vYou will have your share.v I will trouble you for the dictionary.7.表示拒绝，用表示拒绝，用wontvI wont listen to your nonsense.vThe 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w
26、ould比比will语气更温婉等差异。语气更温婉等差异。vI told him that I would go along with him.vIm afraid the journey would be too expensive.vWould like something to eat?vWhen 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。vShall I turn on
27、the light?vShall we meet in the evening?vShall I come in？（你要我进来吗？）？（你要我进来吗？）vMay/Can/Might I come in?（我可以进来吗）（我可以进来吗）vShall they come in or wait outside?vShall he come to see you?vShall+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
28、。警告，威胁，命运或必然的结果等。vYou shall have my answer tomorrow.（允诺）（允诺）vYou shall be sorry for it one day.（警告）警告）vYou shall leave the room or Ill shoot.（警告）警告）vThey shall do as I tell them.（命令或吩咐）命令或吩咐）vNothing shall stop us from carrying out this plan.vYou shall not smoke here.（命令或禁止）（命令或禁止）vDeath is certain
29、to all;all shall die.v死必临万物；万物皆会死死必临万物；万物皆会死 （命运）（命运）vWho touches pitch shall be defiled.v 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。vYou should study the article carefully.vSuch a thing shouldnt be allowed to happen again.vI should help him because he is
30、 in trouble now.vYou 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”。vHe should arrive at noon.vJim should be at home now.vThey should have finished the work by tomorrow.vThey 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
31、，请求建议。vI should say it would be better to try it again.vI should think you are right.vId 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，用于疑问或感叹句中，表示意外，惊异等情绪，与与what,how,why,who连用，且问句不需回答，连用，且问句不需回答，有些相当于修辞性问句。有些相当于修辞性问句。vWhy should I fear?(=I dont fear at all.)vWhat should I see but misery?=I co
32、uld see nothing but misery.)vShould we stand by and do nothing?vShould 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；用在结果状等；用在结果状语从句中，表示语从句中，表示“竟会竟会”vThat things should come to this!竟落到这种地步！竟落到这种地步！vTha
33、t a man should be cruel!人竟会如此残忍！人竟会如此残忍！vWhat have I said that you should get angry?v 我说了什么竟使你生气了？我说了什么竟使你生气了？vIt seems so unfair that this should happen to me.vIt 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
34、示命令，请求，建议，坚持等意义时，v 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)vThe teacher suggested that we should practice speaking English as much as possible.vMy suggestion is that you should go with us.vIt 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
35、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)vIt is important that we should study another foreign language.vIt is a great pity that she should have failed to see such a wonderful performance.3)在在lest,for fear that,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+d
36、o)vHe clears the glass with care for fear that he should break it.vBe quiet in case you should wake the baby.vThey spoke in whispers lest they should be heard.4)should+have done表示过去应该做某事却没做。含表示过去应该做某事却没做。含有有“责备，内疚责备，内疚”之意。之意。vShe should have helped you a lot.vYou should have told him about it.vThey
37、should/ought to have come back yesterday.六六.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，有时也可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vHe dare go deep into the mountains alone.vShe dare say what she thinks.vHe dare not criticize her.vShe never dare speak in public.vNo o
38、ne dare go there.vHow dare you do such a thing?vDare you go home alone?vI wonder if she dare come home.vI 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vHe dares any difficulties.vHe dares me to jump over th
39、e wall.他向我挑战跳过那堵墙他向我挑战跳过那堵墙vI dare you to do it.量你也不敢量你也不敢 vHe dared to swim in the river.vShe didnt dare to tell her mother about it.vI wonder how he dared to say so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.vI will not dare to climb the tree.vHe would never dare to do it.v
40、They have never dared to swim in the lake.七七.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v1）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”v He may have received the letter.v It might have happened last October.v2）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v He may have left when you get there.v She might have died befor
41、e he returns.v3）表示现在已经完成的情况）表示现在已经完成的情况v He might have arrived now.v 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v 朱实施的事情的惋惜朱实施的事情的惋惜vI could have passed the exam,but I was too careless.vIn 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
42、的推测v 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”vShe must have gone through a lot.v 她一定吃了不少苦她一定吃了不少苦 vHe 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表示一种已经做过的但并无比要的行为并无比要的行为vYou neednt hav
43、e watered the flowers,for it is going to rain.2）didnt need to do,表示没有必要做某事，实表示没有必要做某事，实际上也没做。际上也没做。vI didnt need to clean the windows.My sister did it.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“应当正应当正在在可能正在可能正在”vShe might be still thinking of you.vWhat can/could she be doing now?vShe may/might be watering the
44、 flowers.vShe must be watering the flowers.vShe 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.)v 3)would rather(not)+V.v You had better not go by air.v What had we better do?v Hadnt we better leave now?v Had we better not leave now?v Better say yes,if he asks you.v Wouldnt you rather work here?v I would rather have come back yesterday afternoon.
