1、英语一轮复习语法专题语法动词篇专题3 情态动词和虚拟语气情态动词的核心考点1can，be able to 和could(1)can和be able to都表示能力，意思上没多大区别。但can只有现在和过去时，而be able to则有更多的形式。但当成功地完成某一具体动作时，通常不用could而用was/were able to来表示。这时was/were able to 相当于managed to，表示经过一番努力，终于能够完成某事。Her mother can speak French.The wounded man was still able to get to the village
2、 and was saved by the villagers in the end.(2)表示猜测“可能”，一般用于疑问句和否定句。Can the news be true?It cant be true.Someone is knocking at the door.Who could it be?(3)can可以表示理论上的可能性，指常有的行为或情形，意为“有时会”。Anybody can make mistakes.(4)表示请求、允许(表请求时，口语中常用could代替can使语气更委婉，回答时用can)。Can I go now?Could I come to see you to
3、morrow?Yes，you can.(否定答语可用No，Im afraid not.)(5)表示惊异、怀疑、不相信的态度(主要用于否定句、疑问句或感叹句中)。How can that be true？I cant believe my eyes and ears.How could you be so careless?(6)can的特殊用法。can but只有；cant but不得不；cant.too再怎样也不为过，越越好I can but wait.I cant but wait.You cant be too patient to the customers.2may和might的用法
4、(1)表示允许、请求，might比may的语言更委婉一些。May I watch TV now?Yes，you may.(Yes，please.)No，you mustnt.(No，youd better not.)(2)表示可能性时，might比may的可能性小，may表示的可能性比can小(主要用于陈述句、肯定或否定句，疑问句用can代替)。The story may not be true.(3)表示祝愿(不用might)May you succeed!(4)may/might as well最好还是，不妨You might as well do it now.(5)may/might
5、well很可能He may well be late for class.3must，have to和ought to的用法(1)must表示“必须，应该，一定要”。强调主观看法，只有现在时形式，否定式是must not(mustnt)。must开头的问句，其否定回答要用neednt或dont have to代替。表示必然的结果。All men must die.还可表示主语固执、偏要做他人不希望做的事。It cant help；he must do that.(2)have to着重客观需要，能用于更多时态(过去时或将来时)。He will have to be there before t
6、en.(3)ought to表示义务和责任，“应该”，比should语气要强。You ought to take care of yourself.4need和dare的用法(1)need表示“需要，必要”，只能用于否定句和疑问句。在肯定句中，常用must和have to代替。(2)dare表示“敢”，通常用于否定句、疑问句和条件状语从句中。Dare you go home alone at eleven in the evening?(3)need和dare的特殊用法need表“需要”时，可用want，require代替。The desk needs to be repaired./The
7、desk needs repairing.dare作实义动词时，在肯定句中要接to，在疑问句和否定句中to可省去。He dares to catch a snake.I do not dare (to) complain.Do you dare (to) swim in the river?5will和would的用法(1)will表示请求、建议，常用于第二人称。Will you please go with me?表示意愿、决定、允许。I will never do that again.表示习惯性动作或某种倾向，“总是，惯于”，通常用于第三人称。Rosa will always be la
8、te for school.(2)would表示请求、建议，比will委婉，指现在时间，多用于第二人称。Would you like a cup of tea? 表示过去习惯性动作或某种倾向。We would play badminton on Sundays.6shall和should的用法(1)shall用于第一、三人称，在问句中表示征求对方意见或请求。Shall I come in?用于第二、三人称的陈述句中，表示命令或威胁。You shall do as your father says.(2)should表示责任、义务，意为“应该”。表示惊讶语气，意为“竟然”。You should
9、wear slippers in class.用于条件句，表示“假如，万一”，省去if，should可提至句首。Should you be late，apologize to the teacher.7情态动词表示推测或判断的用法下表即是表示推测的情态动词使用的场合：情态动词对现在和未来的推测对过去的推测使用场合mustmustdomust have done肯定句may/mightmay/mightdomay/might have done肯定句、否定句can/couldcan/could docan/could have done否定句、疑问句(could可用于肯定句)should用来表示
10、一种估计的情况“按理会/估计会”should doshould have done肯定句、否定句、疑问句情态动词have done的用法(1)should have done表示“本来应该做某事而实际上未做”，而shouldnt have done则表示“本不应该做某事而实际上做了”。You should have told me about it earlier.You shouldnt have said such words to your parents.(2)ought to have done也表示“本应该”，而ought not to have done则意为“本不应该”。You
11、 ought to have told me about it earlier.You ought not to have said such words to your parents.(3)neednt have done表示“本无必要做某事而实际上做了”。You neednt have walked so quickly since time was enough.(4)could have done表示“本来有可能而事实上未做到”。I could have come on time，but my car broke down on the way.(5)may/might have d
12、one表示“过去可能发生过某事”或“本来应该或可以做某事(实际上没做)”。You might have given him more help，but you were so busy.虚拟语气的核心考点1虚拟语气用于条件状语从句(1)表示与现在事实相反的假设，条件状语从句中的谓语动词用一般过去时(be动词用were)，而主句中的谓语动词用“would/should/could/might动词原形”。If I were you，I would buy that house.If he had time，he should go with you.(2)表示与过去的事实相反，条件状语从句中的谓语
13、动词用过去完成时，主句中的谓语动词则用“would/should/might/couldhave过去分词”。If he had taken my advice，he would have succeeded in passing the examination.(3)表示与将来事实相反，条件状语从句中的谓语动词用一般过去时或“should/were to动词原形”，而主句中的谓语动词则用“would/should/could/might动词原形”。If it were to rain tomorrow，the football match would be put off.(4)当条件状语从句
14、表示的行为和主句表示的行为所发生的时间不一致时，动词的形式要根据它所表示的时间作相应调整。If they had worked hard，they would be very tired now.(从句说的是过去，主句指的是现在)2虚拟语气用于名词性从句(1)虚拟语气在宾语从句中的运用。“wish宾语从句”表示不能实现的愿望，译为“要是就好了”等。表示现在不能实现的愿望，从句中的谓语动词用一般过去时；表示将来不能实现的愿望，从句中的谓语动词用“would/could动词原形”；表示过去不能实现的愿望，从句中的谓语动词用“had过去分词”或“could/shouldhave过去分词”。I wis
15、h it were spring all the year round.I wish I had known the answer.I wish I could fly like a bird.在表示建议、要求、命令等动词后的宾语从句中，谓语动词用“should动词原形”，should可以省略。常见的动词有：suggest，advise，propose，demand，require，insist，request，command，order等。She suggested we (should) leave here at once.The doctor ordered she should be
16、 operated on.(2)虚拟语气在同位语从句和表语从句中的运用。表示建议、要求、命令等的名词，如advice，idea，order，demand，plan，proposal，suggestion，request等，其后的表语从句和同位语从句中谓语动词用“(should)动词原形”，should可以省略。His suggestion that we (should) go to Shanghai is wonderful.My idea is that they (should) pay 100 dollars.(3)虚拟语气在主语从句中的运用。在主语从句中，谓语动词的虚拟语气用“(sh
17、ould)动词原形”的结构，表示惊奇、不相信、理应如此等。It is necessary (important，natural，strange，etc.)that we (should) clean the room every day.It was a pity (a shame，no wonder，etc.)that you (should) be so careless.It will be desired (suggested，decided，ordered，requested，proposed，etc.)that she (should) finish her homework th
18、is afternoon.注意：这种从句表示的是事实。如果人对这种事实表现出惊奇的情感，就可用虚拟语气；反之，如果不表示惊奇等情感，that从句也可用陈述句语气。It is a pity that you cant swim.3虚拟语气在其他场合的运用(1)虚拟语气在as if/as though，even if/even though等引导的表语从句或状语从句中，如果从句表示的动作发生在过去，用过去完成时；指现在状况，则用一般过去时；指将来状况则用过去将来时。He did it as if he were an expert.Even if she were here，she could n
19、ot solve the problem.(2)虚拟语气用于定语从句中。这种从句常用于句型“It is (high)time (that).”中，定语从句的谓语动词用一般过去时(be用were)或“should动词原形”，意为“(现在)该”。Its time that I picked up/should pick up my daughter.Its high time we were going/should go.(3)虚拟语气用在if only引导的感叹句中。If only I were a pilot.If only I had taken his advice.(4)虚拟语气在一些
20、简单句中的运用。情态动词的过去式用于现在时态时，表示说话人谦虚、客气、有礼貌或语气委婉，常出现在日常会话中。It would be better for you not to stay up too late.Would you be kind enough to close the door?用于一些习惯表达法中。Would you like a cup of tea?I would rather not tell you.情态动词、虚拟语气与语法填空对于情态动词在语法填空中考查主要注意情态动词的一般用法以及“情态动词have done”；而对于虚拟语气的考查除了注意情态动词的选用，还需注意
21、一般过去时与过去完成时在虚拟语气中的考查。典题试做1在空白处填入适当的情态动词或括号内所给动词的正确形式1You be Carol.You havent changed a bit after all these years.(2015重庆)答案must解析根据be动词为原形，可判断此处缺少情态动词或助动词。根据后句You havent changed a bit 可知，说话者完全认出了Carol，猜测的语气非常肯定，故填must。2You feel all the training a waste of time，but Im a hundred percent sure later you
22、ll be grateful you did it.(2015陕西)答案may解析由句中的but及后一分句中的a hundred percent sure可知，此处表示语气不强烈的推测，故填may。3Although you find bargains in London，its not generally a cheap place to shop.(2014大纲全国)答案can解析由语境可知，此处表示“你可能在伦敦找到便宜货”，指客观上的可能性。故填can。4Mum：Are they there? Oh，my goodness.I have put them in there when t
23、he phone rang.(2014新课标全国样卷)答案must解析动词原形前常跟情态动词或助动词。根据句意，是对过去的推测，故肯定句中用must have done形式。5Sorry，Mum! I failed the job interview again.Oh，its too bad.You have made full preparations.(2015福建)答案should解析表示“本应该做某事，但事实上却没有做”，用should have done sth.表示，故填should。6I still remember my happy childhood when my moth
24、er take me to Disneyland at weekends.(2014四川)答案would解析由主句中的关键信息 my happy childhood可知，是小时候经常被带去迪斯尼乐园。表示“过去常常”要用情态动词would。7He walked in as if he (buy) the school.And the word quickly got around that he was from New York City.(2012广东)答案had bought解析这是由as if引导的虚拟语气，因为是与过去事实相反，故用过去完成时。8No one be more gene
25、rous；he has a heart of gold.(2013天津)答案can/could解析“No one could be more generous”是否定词和比较级连用，表达最高级含义，can/could可以在否定句中表示推测。9Ellen is a fantastic dancer.I wish I (dance) as well as her.(2015陕西)答案danced解析wish后跟宾语从句时，从句中需要用虚拟语气，主句用一般现在时，从句中用did表示对现在事实的虚拟。故填danced。10It is lucky we booked a room，or we (have
26、) nowhere to stay now.(2015安徽)答案would have解析or引导含蓄虚拟条件句，or后面是主句，相当于if we hadnt booked a room，we would have nowhere to stay now，根据“now”可知，是对现在进行虚拟。故填would have。应对策略11若句中谓语动词为原形，在其前设纯空格题时，注意考虑情态动词与助动词。然后根据句意或句式结构填入恰当的情态动词或助动词。2一旦判断所给动词在句中作为谓语后，就考虑其时态、语态、语气、主谓一致等。注意虚拟语气中的时态，除了if虚拟条件句，还应注意虚拟语气的标志词，如：sug
27、gest，would rather，as if，wish，otherwise，or，but for等。情态动词、虚拟语气与短文改错情态动词与虚拟语气在短文改错中偶有考查。常考查情态动词后的动词形式错误或be动词遗漏；情态动词混用或虚拟语气中情态动词以及时态的错用。典题试做2单句改错(每小题1处错误)1If you are me，would you talk to them？(2015四川)答案arewere解析此处是虚拟语气，表示与现在情况相反，所以要把are改为were。2We must found ways to protect our environment.(2015全国)答案foun
28、dfind解析考查情态动词的用法。情态动词后面要接动词原形。3Thank you for all you have done for me.Mom，though I may often say it，I do love you.(2012四川)答案may后加not解析根据句意，应为“尽管我可能不经常说，但是我真的很爱您”。4My punishment lasted a year.Meanwhile，I found out that with more patience I must make my toys last.My attitude changed from then on.(2012
29、新课标全国)答案mustcould/might解析must必须，一定，用在此处语境不合适。句意为：同时，我发现耐心一些，我可以让我的玩具玩得更久些，所以应用could/might。5I have been practising for three weeks now，but I still couldnt get used to itin fact，Ive nearly killed three people.(2010四川)couldntcant应对策略2做此类改错题时，需注意以下几个方面：(1)看句中情态动词是否运用正确；(2)看是否考查虚拟语气；若是考查虚拟语气，注意分清主句与分句中的时
30、态关系以及不同句式中的虚拟语气构成形式。书面表达中情态动词与虚拟语气易错点聚焦1表达的单调性例如在写一封回信向好友表达建议时，重复使用You should.既显得单调，同时强硬的语气影响了交际效果。我们可以灵活多样地表达建议，如Youd better./You might as well./Why not.？等。2情态动词搭配错误(误)Youd not better quarrel with your neighbors whatever happens.(正)Youd better not quarrel with your neighbors whatever happens.Need I tell him everything that has happened to his father?(误)Yes，you need.(正)Yes，you must.(误)The King was so hottempered that no one dared tell him the bad news.(正)The King was so hottempered that no one dare (dared to) tell him the bad news.3时间错综句的虚拟语气的表达错误从句与主句或上下文所表达的时间不一致，部分考生仍照搬某种形式，因未按照句中所表述的时
