1、语法专题(三)情态动词考 点 归 纳考点一： 情态动词表示能力1表现在的或一般的能力：表示现在的或一般的能力用can或be able to，can比be able to使用得更普遍。can侧重指有能力做某事；而be able to更强调通过努力、克服困难做成某事。A computer cant think for itself；it must be told what to do.He is a native speaker of English，so he can of course speak English quite well.2表示将来的能力：表示将来能力用will be able
2、to。If you have a good sleep，you will be able to work out this problem.如果你睡个好觉，你就能做出这道题。3表示过去的能力：could表示过去一般的能力，即不表示做或未做某事；而was (were) able to do则表示过去有能力并且成功地做了某事，相当于managed to do something/succeeded in doing something。考点二： 情态动词表示推测(可能性)可能性可分为客观的(理论的)可能性和具体事情实际发生的可能性。1客观的(理论的)可能性指并不涉及具体某事是否会发生，此种用法常常
3、可以说明人或事物的特征。can用于肯定句中表示客观的(理论的)可能性，can用于疑问及否定句中则表示实际发生的可能性。The World Wide Web is sometimes jokingly called the World Wide Wait because it can be very slow.A leftluggage office is a place where bags can be left for a short time，especially in a railway station.2表示具体事情实际发生的可能性：表示具体事情实际发生的可能性的层次比较见下表(依次
4、递减)：词形肯定式否定式疑问式must必定，必然 will大概；会不会should/oughttoshould/ought to表示根据常规、事理、经验作出的对现在或未来比较有把握的判断，意为“应该，理应”。can不可能有可能吗？could可疑的可能不可能语气比can弱may“或许，也许”；也未可知，也说不定可能不；或许不might比may还弱比maynot还弱这些词后接动词原形是对现在事情的推测，后接完成式则表示对过去事情的推测；其中can，may/might，should，ought to，must有时还可接进行时表示对现在正在进行的事情的推测。另外，can还可用于否定句、疑问句或感叹句中
5、，表示疑惑、惊讶或不相信等意思；而could既可用于肯定句又可用于否定句、疑问句中；ought to和might表示推测时，并不一定表示过去，而表示可能性弱于他们相应的现在时形式。She might not be in the company.She told me she would go to Shanghai.她可能不在公司，她告诉过我要去上海。Can he have gone to Wuhan?他有可能去武汉了吗？What can he be doing at this moment?这时候他会在做什么？She cant be telling a lie.她不可能在说谎。Your mo
6、ther may be waiting for you to return home.你妈妈可能正等着你回家呢。They must be following us just a little behind us.他们肯定在离我们不远处尾随着我们。You should be doing your exercises instead of watching TV.现在你该做作业而不是看电视。考点三： 情态动词表示请求、允许、允诺1表示征求对方的意见或提出建议时，shall可以用于第一、第三人称的疑问句，will和would用于第二人称的疑问句。分别构成：Shall I/we/he/she/they
7、.？或Will(Would)you(please).?Whats the name?Khulaifi.Shall I spell that for you?2could/would可以用于疑问句表示请求，使语气更加委婉，但其回答语不能再用could/would来回答。Could I borrow your dictionary?Yes，of course you can.3shall也可用于第二、第三人称的肯定句和否定句中，表示说话者命令、警告、允诺或威胁的语气；shall也可用于第二、第三人称表示法律、规定等。What does the sign over there read?“No pe
8、rson shall smoke or carry a lighted cigarette，cigar or pipe in this area.”4can和may都可表示许可，但can较随便，may更正式。Can I use your computer?我用一下你的电脑可以吗？May I have a look at your driving license please，sir?先生，我可以看一下你的驾照吗？考点四： 情态动词表示必要性must常用来表示必要性，意为“必须”；should，ought to也可表示必要性，意为“(义务上)应该”，在语气上比must“必须”弱。表示现在或将来必
9、须做某事用“must动词原形”；表示现在或将来不必做某事时，用dont have to或neednt加动词原形；表示过去没必要做某事时，分为两种情况：当表示过去没必要做某事，但事实上却做了，用neednt have done sth.；当表示过去没必要做某事，而不涉及是否做，可用didnt have to do或didnt need to do sth.或It was not necessary to do sth.等；如表示禁止，则要用mustnt或shouldnt，意为“不应该”。The boss has given everyone a special holiday，so we nee
10、dnt go to work tomorrow.Johnny，you mustnt play with the knife；you may hurt yourself.考点五： 情态动词表示意愿will和would都可表示意志、意愿和决心；will还可表示现在的一种习惯、倾向或趋势；而would则可表示过去反复发生的动作或某种倾向；used to也表示“过去常常”，但它暗含“现在不再”之意。I will never do it again.They asked us if we would do that again.Without water，fish will die.During the
11、 vacation，he would visit me every week.考点六： “情态动词have done”都表示对过去事情的推测或意愿。其具体用法见下表：情态动词完成式用法例句musthavedone表示对过去已经发生的行为进行推测，意为“想必/准是/一定做了某事”。It must have rained last night for the road was quite muddy.canhavedone；cannothavedone表示对过去发生的行为的怀疑和不肯定，通常用在疑问句和否定句中，意为“可能干过某事吗？”；“不可能干过某事”。Can he have gone to
12、his aunts？He cannot have forgotten it.couldhavedone“已经”之意，此外，还可以表示过去没有实现的可能性，意为“本来可以”。I saw Mr.Wang just now.He couldnt have gone to Beijing.may/mighthavedone表示对过去已发生行为的推测，意为“也许/或许已经(没有)”。一般只用于肯定句或否定句中(在否定句中表示“可能不”)，不用于疑问句。用might则表示语气更加不肯定。Its too late.I think he may have gone to bed. He may not hav
13、e finished the work.She might have caught a cold.mighthavedone表示“本来可能”，但实际上没有发生的事。另外，还可以表示“本来应该或可以做某事”之意，含有轻微的责备语气。You should not have swum in that sea.You might have been eaten by fish. You might have given him more help, though you were busy.should/oughtto havedone用于肯定句时，表示本该做某事，而实际上未做，意为“本应该”；用于否
14、定句时，则表示不该做的事反而做了，意为“本不应该”。You should have come to the meeting earlier. You ought to have done this exercise more carefully. You shouldnt have told her the truth. He ought not to have treated his parents like that.neednthavedone表示做了本来不必去做的事，意为“本没必要做某事”；而didnt need to do则表示过去没必要做而实际上也没有做某事。You neednt
15、have taken a taxi here，for it was very near to my house. I didnt need to clean the windows.My brother did it.hadbetterhavedone用于事后的建议，含轻微责备的口吻，意为“当时最好做了某事”，其否定式had better not have done表达相反的含义。You had better have started earlier. You had better not have scolded her.wouldratherhavedone表示“宁愿做过某事”，其否定式w
16、ould rather not have done表达相反的含义，两者都表示“后悔”之意。I would rather have taken his advice. I raised objections at the meeting，but now I would rather not have done that.wouldlike/love tohavedone表示过去愿意做某事，但未做成，意为“愿意做过某事”。I would love to have gone to the party last night but I had to work extra hours to finish
17、 a report.考点七： 情态动词的其他用法1cannot butdo sth.相当于have no choice but to do sth.或can not choose but do sth.，表示“不得不，只好”。2“may/might well动词原形”是一种常用结构，意为“完全能，很可能”，相当于to be very likely to。He may well be proud of his son.他大可为儿子感到自豪。Her appearance has changed so much that you may well not recognize her.她的模样变化太大
18、，你很可能认不出她了。3“may/might as well动词原形”意为“最好，满可以，倒不如”，相当于had better do sth.。You may as well do it at once.你最好马上就做这件事。We may as well stay where we are.我们留在现在的地方倒也不错。cannot(或never等否定词)与enough连用表示“再也不为过”。4may可以用于祈使句，表示祝愿。May we never forget each other.愿我们彼此永不相忘。May you return in safety.愿你平安归来。5should可以用来表示
19、惊讶、失望等情绪，意思是“竟然；竟然会”。It seems so unfair this should happen to me.它发生在我身上似乎很不公平。6must表示“偏要、硬要”做某事，表示虽不情愿但也许可。How old are you，madam?If you must know.Im twice my sons age.7why/howshould结构表示说话人对某事不能理解、感到意外、惊异等意思，意为“竟会”。Why should you be so late today?你今天怎么来得这么晚？How should I know?我怎么会知道？8need和dare的用法need
20、和dare两者既可用作情态动词也可用作行为动词。作行为动词时，有人称和数的变化，可用于肯定句、否定句或疑问句，构成否定和疑问句时要加助动词do，does，did；作情态动词时，没有人称和数的变化(dare的过去式是dared)，直接接动词原形，多用于否定句和疑问句中，构成否定句和疑问句时不用加助动词。dare作行为动词用于否定句和疑问句时，后面的to也可省略，dare还可用于条件句中；need作行为动词时，还可表示“需要”，后接动名词的主动形式表示被动含义。He neednt go now.He doesnt need to go now.He didnt dare(to)do that.He
21、 dared not do that.Your room needs cleaning.Your room needs to be cleaned.解 题 技 巧1.情态动词主要表示说话人的语气或情感，所以我们在解答此类试题的时候，一定要注意说话者的语气，要结合具体的语境来分析和判断。考,例I heard they went skiing in the mountains last winter.It _true because there was little snow there.A. may not beB. wont beC. couldnt be D. mustnt be答案与解析：
22、C本题考查情态动词表推测的用法。根据语境there was little snow there表明对方所说的他们去山里滑雪这件事是不可能的。在表示“不可能”时，cant的语气比may not强，故选C项。2注意“情态动词havedone”的结构，它是历届高考试题中的重点，所以我们一定要牢固地掌握不同情态动词用于此结构所表达的不同含义。考,例Was he present at the meeting?He_not have attended it，for he was busy repairing his computer all the time.A. can B. mightC. shoul
23、d D. must答案与解析：A本题考查“情态动词havedone”表对过去推测的用法。根据语境he was busy repairing his computer all the time可推断他不可能参加这次会议，表示“可能”用can或might，但can的可能性大于might。错 解 分 析1.同类词语意义不清考例1I should have been there，but I_not find the time.A. would B. couldC. might D. should答案与解析：B分析题意可知第二个分句表示过去的某种能力，故本题选B项。错因分析：C项只表示语气上的可能性，与
24、题意不符。考例2I often see lights in that empty house.Do you think I_report it to the police?A. should B. mayC. will D. can答案与解析：A句意：我经常看到那座空房子里有灯亮。你认为我应该把这件事向警局报告吗？should和will分别用于第一人称和第二人称疑问句，表示征询意见。错因分析：同类词语用法不清楚。can/may用于疑问句则表示请求允许。can多用于口语中，may较正式。2语境理解错误考,例Is John coming by train?He should，but he_not.
25、He likes driving his car.A. must B. canC. need D. may答案与解析：Dcome，go，leave，start等趋向动词的进行时表示将来时，所以答语是对这一将来动作作出的推断。may not“可能不，不一定”，根据He likes driving his car.可以看出John可能乘火车来，也可能自己开车来。may not正好符合这一语境。must not“不准”；can not“不可能”；need not“不必”。错因分析：语境理解错误。容易错选B项，但can not表不可能。考 题 对 接.高考题1(2009四川)I dont care w
26、hat people think.Well, you _.Acould BwouldCshould Dmight答案与解析：C句意：我不在乎人们想什么。不对，你应该在乎。根据语境，后半句中省略了一些与前句相同的内容。该题目实际上考查了情态动词的用法。should用以表示义务或责任，如：You shouldnt drink and drive.你不应该喝酒后开车。2(2009北京)One of the few things you _ say about English people with certainty is that they talk a lot about the weather
27、.Aneed BmustCshould Dcan答案与解析：D句意：对英国人，你能确定的几件事情之一就是他们经常谈论天气。need需要；must必须；should应该；can能够，根据语境D项合适。3(2009安徽)Some people who dont like to talk much are not necessarily shy; they _ just be quiet people.Amust BmayCshould Dwould答案与解析：B句意：一些不喜欢多说话的人不一定就害羞，他们可能只是安静的人。4(2009辽宁)The traffic is heavy these da
28、ys, I _ arrive a bit late, so could you save me a place?Acan BmustCneed Dmight答案与解析：D句意：这些天交通很拥挤。我可能迟到，因此请给我留个位子好吗？四个选项中，只有might表示“可能”，用于肯定句。5(2009全国)I cant leave. She told me that I _ stay here until she comes back.Acan BmustCwill Dmay答案与解析：B句意：我不能离开。她对我说过，我得在这里待到她回来。选项A表示能力或许可；选项B表示必须；选项C表示将要；选项D表
29、示可以。根据语境可知，选项B合适。6(2009江苏)He did not regret saying what he did but felt that he _ it differently.Acould expressBwould expressCcould have expressedDmust have expressed答案与解析：C根据语境知道，后半句表示对过去某种情况的揣测，所以首先排除A和B两项。另外，C项表示“本能够做某事，而没有做”；D项表示“过去一定做过某事”。根据语境，知C项合适。7(2009浙江)The doctor recommended that you _ sw
30、im after eating a large meal.Awouldnt BcouldntCneednt Dshouldnt答案与解析：D句意：医生建议说在吃过饱饭后不要游泳。recommend作“建议”解，后面的宾语从句用虚拟语气，谓语动词为“should (not)动词原形“。8(2008浙江)You _ be hungry alreadyyou had lunch only two hours ago!Awouldnt BcantCmustnt Dneednt答案与解析：B句意：你不可能(现在就已)饿了你两个小时前刚吃的午饭。cantdo表示对现在情况的推测，can表推测，常用于否定句
31、和疑问句中；must表推测只用于肯定句中，mustnt意为“禁止，一定不能”。wouldntdo常表示对现在或将来情况的虚拟，neednt do意为“没必要做”。9(2008福建)It is usually warm in my hometown in March, but it _ be rather cold sometimes.Amust BcanCshould Dwould答案与解析：B这里的意思是有时天气可能会相当冷。can用在此处表示可能性。must必须，肯定；should应该；would过去常常。10(2008天津)She _ have left school, for her
32、bike is still here.Acant BwouldntCshouldnt Dneednt答案与解析：A此题考查情态动词表示推测意义的用法。句意：她不可能已离开学校，因为她的自行车还在这儿。根据句意可知选择cant, can/could have done表示对过去的推测，常用于否定句、疑问句中。wouldnt have done常表示虚拟。shouldnt have done本来不应该做而做了；neednt have done本来没必要做而做了。.模拟题1(2009东北三校联考)Why _ it rain on Sunday? We cant go camping as plann
33、ed. What a pity!Ashould Bcan Cmust Dmay答案与解析：C由句意：为什么星期日偏偏下雨？害得我们不能按计划去野营了，真遗憾！知在抱怨，而must则可表示“非得；偏偏”，故C项合句意。2(2009南宁适应性测试) The woman biologist stayed in Africa studying wildlife for 13 years before she returned to her country. Oh, dear! She _ a lot of difficulties.Amay go throughBmight go throughCmu
34、st have gone throughDought to have gone through答案与解析：CC项表示“肯定是经历了”。根据句意：在回国前在非洲呆了13年，表示“对过去所发生事的肯定推测”；D项表示“本该做某事而未做，同should have done”。A、B两项不能表达与过去的关系。3(2009扬州调研)Could I get the passport in 20 days?It depends.Anyway，you _ have my answer tomorrow.Acould BmustCshall Dneed答案与解析：C根据It depends.可知不确定。句意：无
35、论能否，你明天就会听到我的答复。表示对对方的承诺。而shall有此用法。could能够；must必须；need需要。4(2009赣州摸底考试)You_have carried all these parcels yourself. The shop would have delivered them if you had asked them.Aneednt Bmustnt Cshouldnt Dcouldnt答案与解析：Aneednt没必要做而做了，据“The shop would have delivered.”，知选A项。B项中，mustnt不能用于此结构；shouldnt本不该做而做了
36、；couldnt本不可能却做到了。5(2009成都诊断性检测)The old people each _ get a very nice present from our manager on their birthdays.Great! It must be a big surprise to them.Amust BshallCwould Dshould答案与解析：B情态动词shall用于第二、三人称时可以表示允诺、命令、威胁、警告、决心等，本题中的shall表示“允诺，许诺”。其他选项用在这里不合适。6(2009贵州适应性考试)Where is Lily, Lucy? I cannot
37、find her anywhere.She _ have been off long. I saw her clean the window just now.Ashouldnt BcantCmustnt Dneednt答案与解析：B据句意应为“不可能”，所以选B项。shouldnt不该做而做了；neednt没必要做而做了。C项无此用法。7(2009淄博质检)The public transport in Beijing is very convenient now, so there _ be any difficulty in travelling around the city.Acou
38、ldnt BmustntCneednt Dshouldnt答案与解析：D由句意：北京的公共交通很方便。推知下句“因此环城旅行不会困难”。shouldnt(按常理推测)不该。couldnt不可能；mustnt不可以；neednt没必要。8(2009潍坊质检)My mother is a great cook and we _ never get enough of her cookies.Amay BneedCshould Dcan答案与解析：D由句意：好厨师，她做的甜饼我们永远吃不够。知选can能够，表示推测。may也可表示推测，但语气较弱。9(2009西安八校联考)In crowded pl
39、aces like railway stations and airports, you _ take care of your luggage.Amust BmayCwill Dcan答案与解析：A句意：在诸如火车站和机场等人群拥挤之处，你必须照看好你的行李。must 必须。又如：If you cant finish the book by then, you must come and renew it. 如果到时候你看不完这本书，就必须来续借。10(2009大连模拟)Did you attend your sons graduation ceremony yesterday? I_， b
40、ut I had to go to an important meeting.A.used to Bought to Cmust have Dshould have答案与解析：D据句意应为“该做某事而未做”，句中采用了省略形式，但要保持完成时的助动词have，方可表达此意，故选D项。而C项must不能表达此意。11(2009天津河西区)He _ back to work without the doctors permission. Now, he has to stay in bed for a couple of days.Awouldnt have goneBcouldnt have g
41、oneCneednt have goneDshouldnt have gone答案与解析：D由句中后半句“he has to stay in bed for a couple of days.”知“他未遵医嘱”，含有“不该做某事而做了”之意，故选D项。wouldnt have gone本不会做而做了；couldnt have gone本不可能做而做了；neednt have done本不需做而做了。12(2009宁波两地联考)He _ the test again; in the case, his mother will be very disappointed.Ashould fail B
42、must have failed Cmight fail Dcould have failed答案与解析：C句意：他可能考试又不及格；那样的话，他妈妈会很伤心。might表推测，表示不太确定，故选C项。13(2009昆明期末)Shall I book a table for the family reunion dinner ahead of time?Yes, you _. The restaurant is always full, especially during the Spring Festival.Awill BmightCmust Dcan答案与解析：C句意：这家饭店总是人很多
43、，尤其是春节期间。因此“必须”提前订座，故选C项，must必须。14(2009北京宣武区)I promised my daughter she _ get a nice present for her birthday.Will it be a surprise to her?Awould BmustCmight Dshould答案与解析：A由句意：我答应给女儿买件生日礼物。知would表将来，构成过去将来时。15(2009厦门质检)You _ late for yesterdays class meeting，as it was so important.Acouldnt be Bshouldnt beCmustnt have been Doughtnt to have been答案与解析：Doughtnt to have done同于shouldnt have done表示“不该做某事而做了”。由句意知D项合题意。
