情态动词.doc

情态动词北京四中 毕 勤【语法要点】一,在动词(一般动词)之前形成动词的否定,疑问,时态,语法,语态或表示特殊意 义的动词叫做助动词或情态动词.二,分类: be动词, have, do, shall, should, will would, can, could, may, might, must, ought, need, dare, used和had better.三,用法 (一) shall1. shall在纯表示将来的陈述句中只用于第一人称, 在问句中只用于第二人称. 2. 在问句中征求对方的意见和指示的时候常用于第一人称.Shall I post your letter for you? Shall we carry your baggage? (二) should1. 构成过去将来时作为shall的过去时.He asked me whether I should be free tonight.2. 表示主语的义务或责任There should be a double m in swimming.You shouldnt eat between meals, for it will make you fat.同must, have to的区别: must是说者根据其主观意识甚至好恶要求主语”必须”如何如何, 是命令或者强烈的劝告. Have to是说者根据客观事实或环境, 或转述他人的指令或劝告而陈述主语”不得不”如何如何,说者并未掺入丝毫主观的意见. 而should/ought to是说者根据良知,理性,见识推论主语”应该”如何如何. 是属于劝告的范畴.You must study harder. (teacher to student)I have to study harder. (student to friend)You should study harder. (student to student)3. 用在that从句中. 在一些动词后advise, command, demand, insist, intend, order, recommend, request, require, suggest等词后面.She demanded that he (should) leave her room at once.The school requires that all the students (should) learn English. (三) can/could1. 在有其他助动词的时候不能用can,应用be able to.The baby will be able to push the door open.I used to be able to run fast.2. 若指现在或未来在某种条件下才能,但是说话者认为很少有或根本没有这样的条件, 通常用could.We could finish it by 2 oclock if we had the tools.I could have a really good time I had an apartment of my own.3. 一些有关can的词组1)can but/only -只好, 最多不过 We can but/only do our best. I can but lose the money.2) cannot help but 不得不I cannot help but admire your decision. He couldnt help but listen to her talk.(四) would1. 表示的是过去的习惯Sometimes she would bring me little presents without saying why.和used to的区别:would只表示动作. 若是像be, live, have等表示状 态或情况的动词只能用used to. There used to be a tree in front of that building. She used to live here.2. would rather + do + than + doI would rather lose anything than lose this friendship.She would rather stay single than marry somebody she hates.3. would prefer +to doId prefer to travel by train.Id prefer not to pay the fine.Id prefer to start today rather than wait till tomorrow.4. would rather + subject + didId rather you paid cash instead of check.Id rather you came tomorrow.He would rather it were winter now. (五) 表示推测的句子.1. 肯定推测: 用must, may, might, must/may/might have done,He must be the new teacher.They must have come from Shanghai.They may/might have had a cold.2. 否定推测: 用cannot, cannot/couldnt have doneShe cannot be his daughter. She is too old.They cannot/couldnt have caught the 9:15 train, for they left the hotel at 9:20.He cant have heard us. Knock again. (六) need1. 情态动词: 常常用于否定和疑问句You neednt write to him, for he will be here tomorrow.Need I tell you where you are? No, you neednt.2. 实意动词:She needs help. She needs to have an ID card.You dont need to go there to have your exam.3. need doing.(七) dareHe dares to do anything, but this he dare not do.I dare not ask him questions.Dare he tell them what happened yesterday?He doesnt dare to go there by himself.He will never dare to come again.(八) ought to与should 用法类似。【练习检测】1. She _ the book sometime in the past, or she couldnt have answered the question so well.A. can haveB. must have readC. should readD. need reading 2. Tom went on foot, but he _ by bus.A. might be goingB. should goC. could have goneD. ought have gone 3. Let us stay here, _?A. shall weB. will weC. will youD. may you 4. The students soon _ school regulations.A. used toB. be used toC. got use toD. got used to 5. In those days, whenever I had difficulties, I _ Mr Wang for help.A. used to go toB. was used to go toC. would go toD. used to going to 6. Mike _ up at five, but now he gets up at six.A. used to gettingB. would getC. was used to getD. used to get 7. Harry would rather _ than _ the secret.A. die/tellingB. die/to tellC. dead/tellD. die/tell 8. Mary _ the hospital so soon, for she had not got recovered.A. has leftB. didnt leaveC. must have leftD. shouldnt have left 9. I think Helen is at home. No, she _ be at home, for she phoned me from the airport just five minutes ago.A. mustntB. needntC. cantD. ought not 10. There was plenty of time, so she _.A. mustnt have hurriedB. neednt hurryC. mustnt hurryD. neednt have hurried 11. The plant is dead. I _ it more water.A. should have givenB. will giveC. would giveD. must give 12. I missed the bus, so I _ go home on foot.A. mustB. mayC. canD. had to 13. _ you like to see the film?Yes, _.A. Will/Id like toB. Would/Id like to seeC. Would/Id like toD. Do/Id like to 14. There is no light in the room._ he be sleeping?A. MustB. ShallC. CanD. Will 15. Ill do everything I _ you.A. can helpB. can to helpC. must helpD. am to help 16. Hurry up, he _ for you at the school gate now.A. may be waitingB. maybe waitingC. perhaps waitingD. might wait 17. _ he use your bike now?Certainly. Here is the key.A. DoesB. MustC. ShallD. Will 18. Its the second time you have been late this week. You _ earlier.A. could have startedB. ought to startC. might have startedD. should s