情态动词[下学期]

课件25张PPT。 The Usage of the Modal Verbs情 态 动 词The feature（特点） of the modal verbs: 1. 情态动词本身有词义, 但词义不完全. 2. 不能单独作谓语,只能和动词原形一起构成谓语. 3. 情态动词没有人称和数的变化( 除“have to”外). 4. 没有不定式、-ing 分词、-ed 分词形式. He can/could/must/may/might/shall/ should/need/dare/will/would/ought to/ used to + work in that factory.He has to go home now.He had to look after his sick mother.I will have to go home because my mother is ill. can could1.表“能力”Can you lift this heavy box?I couldn’t 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.表“怀疑” “可能性”No, no, it can’t be true. What on earth can this mean?1.can与could用法对比 We thought the story couldn’t be true. / How could you be so careless?4.表 “猜 测”a.can用于疑问句中: 否定答案用can’t; 肯定答案用must.Can he be in the library? He can’t be in the library. He must be at home.b.can+have+P.P.表示对过去的推测 (限于问句中).Can he have said so? 他可能这样说吗?c.can’t+have+P.P.表 示对过去的否定推测She can’t have said such a foolish thing. 她不可能说这样愚蠢的事.d. could+have+P.P: 表示本来能做得到, 但事实上未做到.He could have finished the task on time, but the heavy snow came.e.couldn’t+have+P.P表示对过去某事的否定性猜测He couldn’t have been to that town.注:①could代替can,表示语气较为婉转. Could I use your bike?You could do it this way.②can(能够)=be able to(仅表示能力时),但 be able to 表示经过一番努力后,才能做得到.且有更多的时态.He was a good swimmer, so he _____ swim to the river bank when the boat sank. A. could B. might C. shall D. was able to D. was able tomay与might用法对比: may might1.表“询问”May I …? (=Can I … ?)Might I … ? (=Could I … ?) (但比用may更客气.) 2.表“许可”You may take the boy thereHe told me he might come.(might与told 相呼应.)3.表“可能” “或许”She may not like this place.I’m afraid he might not like this pace.4.表“猜测”a. may(might)+V.表示对现在事情的猜测.(might比 may可能性更小一些.)Now he might know her address. Be careful, you might break the glass.b. may(might)+ have+P.P,表示对过去事情的猜测, 认为某事“可能”发生.(might比may更含蓄,或更不肯定.)He may (might)have played electric game on TV the whole night.(For he looks very sleepy.)注:①may I …? 的答语.肯定: Yes, you can. 否定: No, you mustn’t (语气强硬) No, you may not.或 No, you’d better not.②may(might)用于目的状语从句中.The emperor gave them some gold in order that they might begin their work at once.注:may用于祈使句中表示祝愿May you succeed!May you have good luck!must与 have to用法对比must have to1.表“必须”(主观看法)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.(客观需要)不得不;有多种时态. -It’s raining heavily, we can’t go now. -I think we’ll have to wait till the rain stops.2.疑问句及答语中Must I …? Yes, you must.(一定) No, you needn’t. No, you don’t have to Do you have to go today? Yes, we do. 否定句: You don’t have to worry about that.Have to 用于反意问句You won’t have to worry about rank or spy, will you?He had to wait for the next bus, didn’t he?Her mother is ill. She has to leave here, doesn’t she?3. 带must句子的反意问句He must do it all over again, mustn’t he?(必须)We must finish the work in an hour, needn’t we?(必要)You mustn’t walk on grass, must you?(禁止)①You must be hungry now, _________?= I’m sure you are hungry now.②He must be watching TV now, ______?= I’m sure he is watching TV now.③Tom must have lived here for a long time, _______?= I’m sure Tom has lived here for a long time.④She must have arrived yesterday, __________?= I’m sure she arrived yesterday.*陈述部分的must表示“一定”,“想必”等推测意义时,要根据陈述部分的不定式结构, 在附加疑问部分采用与其相适应的主动词或助动词形式.aren’t youisn’t hehasn’t hedidn’t sheshould与ought to用法对比should ought to1.表“应当”表示劝告,建议You should listen to the doctor’s advice.We should learn from Zhang Hua.表示“有义务或有必 要”做某事You ought to finish your work before you go home.We ought to help each other.2.表可能的猜测They should get home by now.表非常可能的事“总应该”If we start to work right now, we ought to finish it before lunch.3.表 “责备” 或 “惋惜”Should Ought to〉+ have +P.P.→该做，而没有做Should not ought not to〉+ have + P.P. →不该做，而做了The plant is dead. I should have given it more water.You should not have left your baby alone in the house.注:1Should 用于虚拟语气I suggest that you should stay here as if nothing had happened.We should move to a larger house if we had the money. If I was asked to work on Sundays, I should resign.2. Ought to 疑问式及否定式—Ought he to go? —Yes, I think he ought (to).He ought not to leave the work tomorrow.(oughtn’t to leave)(不能说ought to not do)3. shall1) 作助动词，用于第一人称，表示将来，should 是shall 的过去式 We shall start for Beijing tomorrow.2) 作情态动词，A: 用于第一人称，表示征求对方意见或请求 Shall we begin our lesson? Shall I sit here?B: 用于第二、三人称，表示允诺、警告、威胁、命令、决心等。 You wanted justice, so you shall get justice, more than you wanted.(允诺，——威尼斯商人) You shall have a nice present for your birthday.(允诺) You shall be sorry for what you have done,I tell you. （警告） When he comes in nobody shall say a word. (命令) Nothing shall stop us from carrying out this plan. (决心)Need与dare用法对比need dare1.情态动词+V *疑问式 *否定式He need not (needn’t) go.Need we do it again?No, you needn’t do it again.Dare she go out alone at night?How dare you say I am unfair?He dare not say so.2.need/dare+ to do *肯定式 *否定式 *疑问式He needs to go.He doesn’t need to go.Does he need to do it again?He dares to say.He does not dare (to) say.If you dare to jump into the water from here, so dare I.3. did not need to do表示过去没有必要做She didn’t need to attend the meeting yesterday, and she stayed with her children.(她没有参加.)4. needn’t + have + P.P.表示本来不必做，但做了.She need not have attend the meeting yesterday, but she did.(她昨天本不必参加会议，可她参加了.)I didn’t need to go to the bank——I borrowed some money from Mary.(事实上, 我没有去银行.)You needn’t have hurried.Need they have sold the farm?Need you have paid so much?Shall与will用法对比 shall will1.征询对方意见或请求指示,用于第一、三人称. Shall I (we) …? Shall he (she) …? Where shall I (we)wait for you?询问对方的意思或向对方提出要求： Will you (please) …? Won’t you …? Would you like to…?(用would替代will更客气.)—Won’t you go and see the film? —Yes, I think I will.2.表示说话人的“意愿”，有“命令”,“警告”,“强制”, “允许”等，用于第二、三人称，要重读.You shall do what I tell you (to do).Everything shall be done to save the ship.表示 “意志”、“意愿”, 用于各种人称.I won’t do anything you don’t like.would表示过去时间的 “意愿”、“愿望”.Shylock would not take the money earlier.表示惯性动作“总是”、 “惯于”.Fish will die without water.Used to与 would 用法对比1.表示过去的动作、状态,重在现在情况的对比,不一定要有时间状语.used to wouldI used to play cards a lot, but now I seldom play. My hometown is not what it used to be.只表示过去动作的重复, 有明确的时间状语.I would go to see my grandfather on Sunday when he was in the middle school.2.表示过去的习惯, 可互换.When we were very young, we used 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.(×) We used to/would go to the Great Wall five times when we were young.注: used to do 的否定式: usedn’t to do/didn’t use to do (usedn’t也可写作usen’t.) 疑问式:｛Did you use to do…?Used you to do…?｛Didn’t you use to do…?Usedn’t you to do…?Thank you!