1、高考英语情态动词知识讲解一、情态动词的特征本身有词义；不能独立作谓语；后接动词原形一起构成谓语；不随人称和数的变化。二、情态动词各自的基本意义及用法1.can与could用法对比点cancould1.表“能力”Can you lift this heavy box?I couldnt understand what he said at all.2.表“许可”You can use a different material instead.He said I could borrow his bike.3.“怀疑”No, no, it cant be true.What on earth ca
2、n this mean?We thought the story could not be true.How could you be so careless?4.can与be able to的区别could代替can，表示语气更为婉转。eg.: Could I use your bike? Yes, Icancan(能够)= be able to(仅表能力时)，但be able to表示一番努力后，才能做得到，且有更多的时态。2.may与might用法对比点maymight1.表“询问”May I ? (= Can I ?)Might I ? (= Could I?)(但比用may更客气)2
3、.表“允许”You may take the boy there.He told me he might come.(might与told相呼应)3.表“可能”“或许”She may not like this place.Im afraid he might not like this play.注：1.May I?的答语。2.may可表示期望或祝愿May you succeed!3.may (might)用于目的状语从句。肯定：Yes, you may.否定：No, you mustnt不行。（语气强硬）No, you may not或No, youd better not.The emp
4、eror gave them some gold in order that they might begin their work at once.3.must与have to用法对比点musthave to1.表“必须”(主观上)必须；没有过去式，可用于间接引语中。He told me I must do according to what he said.(客观上)不得不，有多种时态。I had to stay at home to look after my younger brother.2.疑问句Must I ? Yes, you must.(一定)No, you neednt./
5、 you dont have to.(不必) (注意否定回答)Do you have to go today?Yes, we do./ No, I dont.You dont have to worry about that.(否定式)4.need与dare用法对比点needdare1.情态v.+动词原形肯定式疑问式否定式He need not (neednt) go.Need we do it again?No, you neednt do it again.He dare not say so.Dare she go out alone at night?How dare you say
6、Im unfair?If he dare do that, hell be punished.I dare say.(固定用法)2.实义v.+ to do肯定式否定式疑问式He needs to go.He doesnt (does not) need to go.Does he need to do it again?No, he doesnt need ot do it again.He dares to say.He does not (doesnt) dare to say.If you dare to jump into the water from here, so dare I.
7、3.did not need to do表示过去没必要做She didnt need to attend the meeting yesterday, and she stayed with her children.(她没有参加)5.should与ought to用法对比点shouldought to1.表“应该”表劝告、建议You should listen to the doctors advice.We should learn from Zhang Hua.“有责任有必要”做某事You ought to finish your work before you go home.We o
8、ught to help each other.2.表“估计”They should get home by now.“非常可能”的事，可译为“总应该”If we start to work right now, we ought to finish it before lunch.注：should还可在虚拟语气中的使用注意：ought to的疑问式及否定式 Ought he to go? Yes, I think he ought to. No, he oughtnt to.否定式：oughtnt to do (不说ought to not do)反义疑问句：oughtnt _?6.shal
9、l与will用法shallwill1.表示强调、征询对方意见或请求指示，用于第一、三人称：I / We / He / She He shall use his discretion.Shall I / We / He / She?Where shall I (we) wait for you?1.询问对方的意思或向对方提出要求：Will you (please)? Wont you?Would you like to.? (would替代will更客气)Wont you go and see the film?你不去看电影吗? Yes, I think I will.不，我想去。2.表示说话人
10、的“意愿”有“命令”“警告”“强制”“允诺”“决心”等强调“重要性、责任感时”，用于第一、二、三人称。You shall do what I tell you(to do).我叫你干什么你就干什么。Everything shall be done to save the ship.一定要竭尽全力来拯救这艘船。2.表示“意志”“意愿”，用于各种人称：I wont do anything you dont like.我不会做任何你不喜欢的事。Would表示过去时间的“意志”“意愿”Shylock would not take the money earlier.夏洛克先前是不肯要钱的。7.used
11、 to与would用法used towould1.表示过去的动作、状态，重在与现在情况的对比，不一定要有时间状语。Iused to play cards a lot, but now seldom.My hometown is not what itused to be.1.只表示过去动作的重复，有明确的时间状语。Iwouldgo to see my grandfather on Sunday whenhe was in the middle school.2.只接表动作的动词，不接表认识或状态动词。2.表示过去的习惯有时可互换：When we were very young, we used
12、 to / would go skating every winter.3.表示过去的次数时，不能使用：()We went to the Great Wall five times when we were young.() Weused togo /wouldgo to the Great Wall five times when we were young.注：used to do的否定式：usednt to do或didnt use to do (usednt也可写作usent)疑问式：Did you use to do? Didnt you use to do?Used you to
13、do?Usednt you to do?三、情态动词表推测1.大多数情态动词（除表能力、许可、意志外），都可以表示推测，其程度有差异。按可能性程度的高低排列为：must willwould ought toshould完全肯定 完全可能 很可能cancouldmaymight可能 有可能2.区分情态动词的否定含义：2may not或许不、可能不might not可能不cant不可能mustnt不许、禁止shouldnt不应该neednt不必3.情态动词表推测具体运用：情态动词可以对现在、进行、过去推测。S主+情态动词+ be + adj对“性质”“特征”的推测S主+情态动词+ be + n对“
14、职业”“事物”的推测S主+情态动词+动词原形对经常性行为的推测S主+情态动词+ be + V-ing对进行着的行为的推测S主+情态动词+ have + PP对过去的行为的推测情态动词表推测时：1.can只能用于否定句和疑问句。2.must只能用于肯定句（它的否定句和疑问句其实就用can来代替）。3.如句中有情态动词+完成时，一定是对过去的推测。4.句中如有表示不肯定的话语，如I am not sure; I dont know之类时，常选may /might的各种形式。4.表示反劝的特殊的表推测形式could + have + P.P.表示本来能做到，但事实上没有做到。He could hav
15、e finished the task on time, but the heavy snow came.couldnt +have + P.P.表示本来不能做到，但已经做到了。She could not have covered the whole distance, but in fact she arrived ahead of time.neednt + have + P.P.表示本不必做的，但已经做到了。She neednt have attended the meeting yesterday, but she did.should/ought to +have + P.P.表示该
16、做而没有做。The plant is dead.I should/ought to have given ot more water.shouldnt/ oughtnt to +have + P.P.表示不该做而做了。You oughtnt to / shouldnt have taken her bike without permission.5.注意：must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）must + have + P.P.表示对过去肯定的推测，“一定是”The road is wet.It must have rained yesterday.can + ha
17、ve + P.P.表示对过去的推测（限于问句中）Can she have said so?他可能这样说吗？cant + have + P.P.表示对过去的否定推测He cannot have said such a foolish thing.四、情态动词表推测的反意疑问句1.情态动词表推测的反意疑问句，简单来说，就是以情态动词后的时态为淮，如句子里有明确的时间状语，则以其为准。2.以must为例：e.g.: 1.You mustbehungry now,arentyou?2.He mustbe watching TV,isnthe ?3.Tom musthave livedher for a long time,hasnthe ?4.She must have arrivedyesterday,didntshe?注：如选择题中（以She must have arrivedyesterday,didntshe？为例）既有didnt she又有hasnt she则以didntshe？为最佳答案。
