1、专题六情态动词、虚拟语气情态动词一、can和could的用法1表示能力Her mother can speak French.2表示客观可能性Anybody can make mistakes.3表示许可(多用于口语)Can I go now?4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 you be so careless!5can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 custo
2、mers.二、may和might的用法1表示允许、请求May I watch TV now?Yes，you may.(Yes，please.)No，you mustnt.(No，youd better not.)2表示可能性(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!4may/might as well最好还是You might as well do it now.5may/might well很可能He may well be late for class.三、must，h
3、ave to和ought to的用法1must(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。(2)must表示必然的结果。All men must die.(3)must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.2have 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 ten.3ought to表示义务和责任，“应该”，比s
4、hould语气要强。You ought to take care of yourself.四、need和dare的用法1need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。2dare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?3need和dare的特殊用法(1)need表“需要”时，可用want，require代替。The desk needs to be repaired./The desk needs repairing.(2)dare作实义
5、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.五、will和would的用法1will(1)表示请求、建议，常用于第二人称。Will you please go with me?(2)表示意愿、决定、允许。I will never do that again.(3)表示习惯性动作或某种倾向，“总是，惯于”，通常用于第三人称。Fish will die out of water.2would(1)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?(2)表示过去习惯性动
6、作或某种倾向。We would play badminton on Sundays.六、shall和should的用法1shall(1)用于第一、三人称，在问句中表示征求对方意见或请求。(2)用于第二、三人称表示命令或威胁。You shall do as your father says.2should(1)表示责任、义务，意为“应该”。(2)表示惊讶语气，意为“竟然”。You should wear slippers in class.(3)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、.七、“情态动词have done”的用法1must have done sth.；can(could) have done sth.(1)must have done sth.表示对过去已经发生的事情的有把握的推测，意思是“想必、准是、一定做了某事”，只用在肯定句中。It must have rained last night，for the ground is wet.(2)can(could) have done sth.表示对过去发生的动作的怀疑和不肯定，通常用在否定句和疑问句中。He cant have forgotten it.2neednt have done sth.；didn
8、t need to do sth.(1)neednt have done sth.表示已完成不需要完成的动作。You neednt have waken me up.I dont have to go to work today.(2)didnt need to do sth.表示没有必要做而实际上也没有做某事。I didnt need to clean the windows.My brother did it.3may/might have done sth.may/might have done sth.表示对过去已发生的动作的推测，意为“也许/或许已经”。Im not sure.He
9、might have said so at the conference.4should have done sth.should have done sth.表示本来应该做某事而实际上未做。You should have told him about it.5had better have done sth.；would rather have done sth.；would like/love to have done sth.(1)had better have done sth.表示事后的建议，含轻微责备的口吻，意为“当时做了某事就好了”，其否定形式had better not hav
10、e done sth.表达相反的含义。(2)would rather have done sth.表示“宁愿当时做某事”，其否定形式would rather not have done sth.表达相反的含义，两者都含有“后悔”之意。I would rather have taken his advice.(3)would like/love to have done sth.表示过去愿意做某事，但未做成。I would love to have gone to the party last night，but I had to work extra hours to finish my re
11、port.虚拟语气一、以if条件从句为虚拟语气标志时态从句动词形式主句动词形式与现在事实相反didwould/could/should/mightdo与将来事实相反(1)did(2)were to do(3)should dowould/could/should/mightdo与过去事实相反had donewould/could/should/mighthave done注意以下两个方面：1含蓄条件句有时虚拟语气并不总是用if引导的条件句来表示，而是通过一些词或短语表示出来。这些词或短语引出的条件与if引导的条件句意义相似，如but for，with，without，otherwise，or，
12、but等。其中but for相当于if it were not for/if it had not been for，表示“要不是”。He wouldnt have survived but for the neighbours timely help.2在虚拟条件句中有时if是可以省略的，当if被省略后，要将从句中的were，had，should置于句首，构成倒装结构。Were he here，he could settle the issue.二、虚拟语气在名词性从句中的用法1宾语从句(1)suggest等表示建议、愿望、命令等的动词后跟的宾语从句要使用虚拟语气，从句谓语的结构为“shou
13、ld动词原形”，其中should可以省略。类似用法的动词还有order，request，advise，require，insist，demand，command等。The doctor suggested that he (should) take more rest.(2)would rather后的宾语从句would rather后的从句常用一般过去时表示与现在或将来相反的情况；用过去完成时表示与过去相反的情况。Id rather you left tomorrow.2主语从句在“It is/was/has/had been suggestedthat引导的主语从句”中，主语从句要用虚拟语
14、气， 即“should动词原形”结构，其中should可以省略。和suggest用法一样的动词还有demand，order，advise，require，propose等。另外，在“It is/was important(necessary，desirable，advisable等)that引导的主语从句”中，从句也常用虚拟语气，谓语用“should动词原形”结构，其中should可以省略。It is suggested that the building (should) be pulled down.It is necessary that a doctor (should) be sen
15、t for at once.3表语从句当suggestion，order，proposal，demand等名词作主语时，其后的表语从句中要用虚拟语气“should动词原形”结构，其中should可以省略。My advice is that you (should) give up smoking.4同位语从句在suggestion，advice，order，proposal，demand等名词后跟的同位语从句中要用虚拟语气，谓语用“should动词原形”结构，其中should可以省略。His suggestion that we (should) set off at 500 am.is no
16、t good enough.三、虚拟语气的特殊句型It is (high/about) time (that) sb. did sth.(that可以省略)表示“是某人做某事的时候了”，此句型应用虚拟语气，从句用一般过去时。另外，也可使用It is (high/about) time (that) sb.should do sth.结构，其中should不能省略。It is 1100 now.It is high time (that) you went/should go to bed.情态动词答题技巧技巧1意义判断法所谓意义判断法就是分析语境并确定应填情态动词的含义。因此熟练掌握每个情态动
17、词的意义和用法是做题的前提。考题印证You_park here！Its an emergency exit.(2010重庆，21)Awouldnt BneedntCcouldnt Dmustnt答案D解析句意为：你不能把车停在这里！这是一个紧急出口。wouldnt不会；neednt没有必要；couldnt不能够；mustnt不准，禁止。故选D项。技巧2句型判断法有些情态动词需要用在特定的句型中，如may表示推测时，往往用在肯定或否定句中；must表示推测只能用于肯定句中。运用此法就是通过分析所给句子的句型特点，选用具有特定句型特点的情态动词。考题印证 May I take this book
18、out of the reading room?No，you_.You read it here.(2010陕西，23)Amightnt BwontCneednt Dmustnt答案D解析句意为：我可以把这本书带出阅览室吗？不可以，你一定不能带出去。你就在这里读。mustnt表示强烈的禁止。技巧3语气判断法情态动词主要表示说话人的语气、情感或态度，所以在解答此类试题时，一定要注意说话者的语气(这也是解题的难点)，这就要求正确理解句子，从说话者的角度去考虑问题，结合具体的语境来分析和判断，最后确定所需情态动词是否符合特定的情感需要。考题印证Just as we were sitting down
19、 to have dinner，the telephone_ring.A.must B.couldC.might D.need答案A解析考查情态动词。must在此表示说话人的愿望或感到不耐烦，意为“偏要”。句意为：正当我们要坐下来吃饭时，偏偏电话铃响了。技巧4人称判断法有些情态动词在表达某个意义时，要与特定的人称连用，这为我们选择正确答案提供了方向。考题印证I havent got the reference book yet，but Ill have a test on the subject next month.Dont worry.You_have it by Friday.(2010
20、江苏，25)Acould BshallCmust Dmay答案B解析句意为：我还没有弄到参考书，但是下个月我将参加这门学科的测试。不要担心，到星期五时你就有了。could能够；shall在句中表示“允诺”；must必须；may也许，可以。虚拟语气答题技巧技巧1句型提示法虚拟语气可以用在状语从句、名词性从句、定语从句中，在不同的从句中，虚拟语气用不同的动词形式来体现，如if非真实条件句(分三种情形)，wish后的宾语从句，It is time that.的定语从句等。所以，掌握了各类从句中虚拟语气的动词形式，就基本上掌握了虚拟语气的用法。考题印证If we_the other road，we m
21、ight have arrived here in time for the meeting.(2010陕西，15)A.take B.had takenC.took D.have taken答案B解析句意为：如果我们走另一条路的话，我们或许能够及时到达这里参加这次会议了。根据主句的谓语动词might have arrived可以推出，本句是与过去事实相反的虚拟语气，所以if条件句中应该用过去完成时。技巧2特定词汇暗示法英语中某些短语如If it were not for/had not been for, but for., if only., without等，往往要采用虚拟语气，它们对于解
22、答试题有很大的帮助，掌握了这些要点知识，做起题来也就很容易了。考题印证Thank you for all your hard work last week.I dont think we_it without you.Acan manage Bcould have managedCcould manage Dcan have managed答案B解析could have done表示本能够做某事(但没做)。1Churchill warned Hitler，“If you dare to invade Britain，you _pay for it with great cost.”Awill
23、BshallCmay Dshould答案B解析考查情态动词的用法。句意为：丘吉尔警告希特勒，“如果你胆敢侵略英国，你要为此付出巨大的代价。”shall用于第二、第三人称，表示说话人给对方命令、警告、允诺或威胁。故选B项。2Whats your feeling now?I am terribly sorry.If only I _here yesterday!Acame Bwould have comeChave come Dhad come答案D解析考查if only的用法。if only要是就好了，从时间状语yesterday来看，这是对过去所发生事情的虚拟，所以用过去完成时。3If you
24、_smoke，you could at least go to the smoking area.Acan Bmust Cwill Dshall答案B解析考查情态动词的特殊用法。must在这里表示“偏偏，非要”。句意为：要是你非吸不可的话，至少得到吸烟区里吸。4At a construction site in our city the workers have uncovered an ancient wall that _ to keep the enemy out of the city，but it requires further evidence.Amight have funct
25、ioned Bwould have functionedCmust have functioned Dshould have functioned答案A解析might have done是对过去不太肯定的猜测。句意为：在市里的一处工地上，工人们挖出了一道可能是以前用来御敌的城墙，但这还有待进一步验证。根据句意选A。5.Johnson，come and look at the sea！It is beautiful，isnt it?Absolutely！If only I _here by the sea.A.lived B.liveC.had lived D.will live答案A解析由语境
26、可知，if only后的情形是与现在的事实相反，此时的谓语动词用过去时。6Im surprised that your story _ the first prize.Ashould win Bcan winCshould have won Dcan have won答案C解析句意为：你的小说竟然获得了一等奖太让我吃惊了。should在此处意为“竟然”；由语境知win这一动作发生在主句的谓语动词前，故should后接动词的完成时。7What is a leftluggage office?It is a place where luggage_be left for a certain per
27、iod of time，especially at a bus or a train station.Acan BshouldCmust Dwill答案A解析考查情态动词的用法。句意为：什么是行李寄存室？它是行李在某一段时间被存放的地方，尤其是在公共汽车站或火车站。由句意知选A。8Can I pay the bill by check?Sorry，sir.But it is the management rules of our hotel that payment _be made in cash.Ashall BneedCwill Dcan答案A解析考查情态动词。shall用在条约、规章、
28、法令等文件中表示义务或规定，一般用于第三人称，意为“应该，必须”。句意为：我可以用支票付账吗？对不起，先生。只是这是我们旅馆的管理规定：付账必须使用现金。9If passersby _ a blind eye to the injured little Yueyue in Foshan，Guangdong，she _ alive now.Adidnt turn；would beBhadnt turned；would beCdidnt turn；would have beenDhadnt turned；would have been答案D解析考查虚拟语气。由常识可知，小悦悦事件已是过去的事情，所
29、以这是对过去发生的事情的虚拟，所以从句用过去完成时，即had done，主句用would have done。10It _have been her to leave her child alone.She isnt such a person.Acouldnt BmustntCmightnt Dwouldnt答案A解析考查情态动词的用法。由语境可知，leave应该是过去的一个动作，很显然这是对过去发生事情的否定猜测，所以应该用couldnt have done。句意为：她不可能把孩子单独留在家里。她不是那种人。11The government urged that every effort
30、_ to bring down house prices.Ashould make Bwould be madeCbe made Dmust be made答案C解析考查虚拟语气。此处urge后的宾语从句用“(should)动词原形”的形式，should被省略；宾语从句为make every effort to do sth.的被动形式。句意为：政府紧急督促要尽一切努力降低房价。12.They must have enjoyed themselves there，otherwise they _ so long.A.cant have stayed B.wouldnt have stayedC
31、.cant stay D.wouldnt stay答案B解析由“must have enjoyed”可知otherwise后的情况是与过去的事实相反的，故谓语动词应用would have done。13He _ the first place again，in which case，his mother will be more than happy.Acant win Bwould have wonCmight win Dcould have won答案C解析考查情态动词的用法。此处might表推测。句意为：他可能又获得了第一名，如果那样的话，他的母亲会很高兴。14_more energy
32、to my study instead of being crazy about Internet games，I would be sitting in a comfortable office now.AIf I devoted BHad I devotedCWould I be devoted DShould I be devoted答案B解析考查错综虚拟句。此处从句用过去完成时，表示与过去的事实相反，如果省略if要用倒装句；主句用“would动词原形”的形式，表示与现在的事实相反。15She_well let out the secret，for she looked very upset when seeing me.Acan Bmay Cmust Dshall答案B解析考查情态动词的用法。may well很可能，极有可能。句意为：她很可能说出了这个秘密，因为她看见我时她看起来很难过。