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第二部分第二部分 语法考点突破语法考点突破第七讲情态动词和虚拟语气第七讲情态动词和虚拟语气一、情态动词的基本用法一、情态动词的基本用法情态情态动词动词用法用法例句例句must(1)表示禁止表示禁止(用用于否定句于否定句)。You mustnt park here！Its an emergency exit.(2)表必要性，表必要性，意为意为“必须必须”。Shall I inform him of the change of the schedule right now?I am afraid you must，in case he comes late for the meeting.(3)表示偏执，表示偏执，固执，意为固执，意为“非非得，偏要得，偏要”。If you must go，at least wait until the storm is over.情态动情态动词词用法用法例句例句can和和could(1)表示表示“能力能力”。No one can be compared with Yao Ming in playing basketball.Oh，you are really his big fan.(2)表示惊讶表示惊讶,常用常用在否定句和疑问句在否定句和疑问句中。中。How could you do such a silly thing？情态动情态动词词用法用法例句例句can和和could(3)表示礼貌地请表示礼貌地请求别人做某事，意求别人做某事，意为为“能，可以能，可以”。This dish is really delicious.Could you please say it in Chinese?Sure，we call it“doufu”What should I wear to the party?Well，it isnt very formal.You can wear whatever you like.情态动情态动词词用法用法例句例句can和和could(4)cannot.too/enough表示表示“无无论论也不过分也不过分”;“越越越好越好”。You cant be too careful while driving.情情态态动动词词用法用法例句例句shall(1)用于第一、第三人称疑用于第一、第三人称疑问句中问句中,表示说话人征求对表示说话人征求对方的意见和向对方请示。方的意见和向对方请示。Shall I go out for a walk after supper?(2)用于第二、第三人称陈用于第二、第三人称陈述句中，表示说话人给对述句中，表示说话人给对方的命令、警告、允诺或方的命令、警告、允诺或威胁。威胁。Will you read me a story，Mummy?OK.You shall have one if you go to bed as soon as possible.情情态态动动词词用法用法例句例句may和和might(1)may和和might表示表示“许可许可”,“可能性可能性”,“祝愿祝愿”等意义。等意义。May I take this book out of the reading room?No，you mustnt.You read it in here.(2)“may as well动动词原形词原形”意为意为“最好，最好，倒不如倒不如”。If you think the price of beef is too high，you may as well buy some pork.It depends on you.情情态态动动词词用法用法例句例句will和和would(1)表示意志、意表示意志、意愿和决心。愿和决心。I have told him again and again to stop smoking，but he will not listen.(2)will可以表示可以表示一种习惯的动作一种习惯的动作,有有“总是总是”或或 “总要总要”之意。之意。Every morning he will have a walk along this river.情态动词情态动词用法用法例句例句will和和would(3)would可以表示可以表示过去的习惯动作，过去的习惯动作，比比used to正式，但正式，但没有没有“现已无此习现已无此习惯惯”的含义。的含义。When we worked in the same firm several years ago，we would often go to the cinema together.二、情态动词表推测二、情态动词表推测情情态态动动词词用法用法例句例句mustmust表示推测时只能表示推测时只能用于肯定句中，意为用于肯定句中，意为“一定，必定一定，必定”，表，表示十分肯定的语气示十分肯定的语气(在在疑问句中或否定句中疑问句中或否定句中要用要用can/could)。Its the office！So you must know eating is not allowed here.Oh，sorry.情态情态动词动词用法用法例句例句can(1)can用于肯定句中表示用于肯定句中表示客观的可能性，意为客观的可能性，意为“有有时会时会”；(2)用于疑问句中可以表示用于疑问句中可以表示推测，意为推测，意为“可能可能”，有，有时表示一种惊讶的语气；时表示一种惊讶的语气；(3)用于否定句中也可以表用于否定句中也可以表示推测，示推测，cant意为意为“不可不可能能”，语气很强烈。，语气很强烈。It is usually warm in my hometown in March, ,but it can be rather cold sometimes.Mr.Bush is on time for everything.How can it be that he was late for the meeting?It cant be the postman at the door.Its only six oclock.情态动词情态动词用法用法例句例句may/mightshould(1)may/might用于肯定用于肯定句中可以用来表示不十句中可以用来表示不十分肯定的推测，意为分肯定的推测，意为“有可能有可能”；(2)用于否定句中也可以用于否定句中也可以表示推测，表示推测，may not意意为为“可能不可能不”，表示一，表示一种不太确定的语气。种不太确定的语气。(2013高考北京卷高考北京卷)You neednt take an umbrella.It isnt going to rain.Well，I dont know.It might do.should用来表示推测时用来表示推测时意为意为“应该应该”，即含有，即含有“按道理来说应当如按道理来说应当如此此”的意思。的意思。There shouldnt be any difficulty about passing the road test since you have practiced a lot in the driving school.三、情态动词三、情态动词have done情态动词情态动词have done用法用法例句例句musthave donemay/might have done表示对过去已经发生表示对过去已经发生的行为进行推测的行为进行推测,意为意为“一定做了某事一定做了某事”。(2013高考辽宁卷高考辽宁卷)Harry is feeling uncomfortable.He must have drunk too much at the party last night.表示对过去已发生行表示对过去已发生行为的推测为的推测,意为意为“也也许许/或许已经或许已经(没有没有)”。一般用于肯。一般用于肯定句或否定句中。定句或否定句中。Sorry，Im late.I might have turned off the alarm clock and gone back to sleep again.情态动词情态动词have done用法用法例句例句can.havedone/cannot have donecould have done表示对过去发生的表示对过去发生的行为的怀疑和不肯行为的怀疑和不肯定，通常用在否定定，通常用在否定句和疑问句中。句和疑问句中。(can换成换成could时时语气较委婉语气较委婉)I cant find him anywhere.Where can he have gone?The boy cant have finished reading the book so soon because it is difficult even to an adult.本来能够而没有做本来能够而没有做(2012高考北京卷高考北京卷)We could have faced the difficulty together，but why didnt you tell me？情态动词情态动词have done用法用法例句例句might have doneshould/ought to have done表示本来可能表示本来可能,但实际上没有发生但实际上没有发生的事情。的事情。You should not swim in that sea.You might have been eaten by a shark.(1)用于肯定句时，用于肯定句时，表示本该做某事而表示本该做某事而实际上未做；实际上未做；(2)用于否定句时，用于否定句时，则表示不该做的事则表示不该做的事反而做了。反而做了。You shouldnt have done it so carelessly.You ought to have returned the book earlier.情态动词情态动词have done用法用法例句例句neednt have done表示做了本来不必表示做了本来不必去做的事，去做的事，“没必没必要做而做了要做而做了”。注意注意didnt need to do表示表示“没必要没必要做而实际上也没有做而实际上也没有做某事做某事”。You neednt have brought the book because Tom has one here.I didnt need to buy the dictionary.I had a copy at home.一、一、if条件从句中的虚拟语气条件从句中的虚拟语气类别类别用法用法例句例句if引导引导的条件的条件从句从句与现与现在事在事实相实相反反从句谓语动词：从句谓语动词：过去式过去式(be用用were)主句谓语动词：主句谓语动词：should/would/could/might动词原形动词原形(2012高考湖南卷高考湖南卷)Sorry, I am too busy now. If I had time, I would certainly go for an outing with you.很抱歉，我现在非常忙。很抱歉，我现在非常忙。若我有时间，我将一定若我有时间，我将一定与你外出郊游。与你外出郊游。类别类别用法用法例句例句if引导引导的条件的条件从句从句与过与过去事去事实相实相反反从句谓语动词：从句谓语动词：had过去分词过去分词主句谓语动词：主句谓语动词：should/would/could/mighthave过去分词过去分词(2012高考山东卷高考山东卷)If we hadnt made adequate preparations，the conference wouldnt have been so successful.如果我们没有充足地准如果我们没有充足地准备，大会将不会如此地备，大会将不会如此地成功。成功。类别类别用法用法例句例句if引导引导的条件的条件从句从句与将与将来事来事实相实相反反从句谓语动词：从句谓语动词：过去式过去式/were不定式不定式/should动动词原形词原形主句谓语动词：主句谓语动词：should/would/could/might动词原形动词原形(2012高考安徽卷高考安徽卷)Grace doesnt want to move to New York because she thinks if she were to live there, she wouldnt be able to see her parents very often.Grace不想搬到纽约，因不想搬到纽约，因为她想如果要是住那里，为她想如果要是住那里，她将不可能经常地见到她她将不可能经常地见到她的父母。的父母。类别类别用法用法例句例句if引导的引导的条件从条件从句的倒句的倒装装混合条混合条件句的件句的虚拟语虚拟语气气如果在表示虚拟语气如果在表示虚拟语气的条件句中含有的条件句中含有were，had或或should，可将，可将if省略省略,然后将然后将were,had或或should移至主语之前。移至主语之前。Had we made a great effort we might have succeeded.(If we had made a great effort.)要要是我们付出巨大的努力是我们付出巨大的努力,也许我们已经成功了。也许我们已经成功了。有时条件句的动作与有时条件句的动作与主句动作发生的时间主句动作发生的时间不一致，这时动词的不一致，这时动词的形式应根据它们表示形式应根据它们表示的时间加以调整。的时间加以调整。If it had rained last night,it would be very cool today.如果昨晚下雨如果昨晚下雨了，今天将会很凉爽。了，今天将会很凉爽。二、含蓄条件句的虚拟语气二、含蓄条件句的虚拟语气有时假设的情况并不以条件从句表示，而是由有时假设的情况并不以条件从句表示，而是由otherwise，but,or，without，but for等来引导。等来引导。I would have come sooner but I didnt know that they were waiting for me.我本该早一些到，但我不知道他们在等我。我本该早一些到，但我不知道他们在等我。I couldnt have gone through that bitter period without your generous help.假如当时没有您慷慨相助，我就不会度过那段艰难的时期。假如当时没有您慷慨相助，我就不会度过那段艰难的时期。三、虚拟语气在名词性从句中的应用三、虚拟语气在名词性从句中的应用类别类别用法用法例句例句宾宾语语从从句句demand，suggest，order，insist后接的从句中动词为后接的从句中动词为“(should)动词原形动词原形”。Teachers recommend parents not allow their children under 12 to ride bicycles to school for safety.wish后的从句中的谓语可后的从句中的谓语可用一般过去时、过去完成用一般过去时、过去完成时和时和should/would动词动词原形原形,它们分别表示与现在、它们分别表示与现在、过去和将来情况相反。过去和将来情况相反。How much of the foreign experts speech have you understood?Next to nothing.I wish I had worked harder at English.类别类别用法用法例句例句主语主语从句从句表语表语从句从句和同和同位语位语从句从句在在“It is necessary/important/strange/suggested/demanded/ordered/requestedthat从从句句”中，从句中的谓语动词中，从句中的谓语动词用用should动词原形。动词原形。It is strange that such a person should be our friend.在在suggestion,proposal,order,plan,idea,request,advice等名等名词后的表语从句和同位语从词后的表语从句和同位语从句中要用虚拟语气句中要用虚拟语气,其构成是其构成是“should动词原形动词原形”,should可以省略可以省略My idea is that we (should) think it over before accepting it.We all agreed to his suggestion that we (should) go to Dalian for a visit.四、其他句型中的虚拟语气四、其他句型中的虚拟语气类别类别用法用法例句例句Its time that.would ratherIt is (high) time(that).句型中谓语动词句型中谓语动词用一般过去时或用一般过去时或should动词原形。动词原形。Its high time that we devoted ourselves to environmental protection and ecological improvement. would rather所接的从句中所接的从句中的谓语动词用一般过去时的谓语动词用一般过去时(对现在虚拟对现在虚拟)或者过去完成或者过去完成时时(对过去虚拟对过去虚拟)。I would rather youstayed at home now.类别类别用法用法例句例句if onlyas ifif only后面的谓语动词常用一后面的谓语动词常用一般过去时般过去时(对现在虚拟对现在虚拟)、过去、过去完成时完成时(对过去虚拟对过去虚拟)与过去将与过去将来时来时(对将来虚拟对将来虚拟)，表示强烈，表示强烈的愿望。的愿望。If only our dream had come true！as if引导的状语从句中动词可引导的状语从句中动词可以用过去时或过去完成时表以用过去时或过去完成时表示虚拟。示虚拟。They are talking as if they had been friends for years.
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