Grammar情态动词生活中的情态动词 Descriptors: describe the pictures by making up sentences including modal verbs.2.You should listen to the teacher carefully.1.You had better take an umbrella in case it rains.4.His bike is broken. He has to walk to school.3.Can you tell me where the supermarket is?概述情态动词表示说话人的某种语气或感情 ,不能单独作谓语,必须和行为动词或连 系动词一起构成谓语。情态动词没有人 称和数的变化。(be able to/have to例外）I can speak English very well.He can speak English very well.He cant be a teacher.情态动词总汇：can / could / be able tomay / mightwill / would (used to)shall / should (ought to)must / have toneed / dare一、can 和could (be able to)1.表示能力，意为“能，会”, could 为can 的过去式 。其否定式为can not / cannot, could not或简写成 cant, couldnt Tom can swim very well now. Tom couldnt swim very well at the age of 4.can与be able to的区别：1）can只有过去式，而be able to有各种时态2）can表示具备某种能力，而be able to则表示经过努力成功地做到某事If he studies hard, he will be able to pass the final exam.At first he didnt agree with me, but I was able to persuade him.2. 表示请求（可不可以）和许可（可以），表示请求时用can和could都可，could语气更委婉，而不是can的过去式；表示许可时只能用can,不能用could.-Can / Could I come in?-Yes, you can.3. （表示猜测）可能多用于疑问句和否定句中，can的可能性比could大，其否定形式是cant / couldnt（不可能 ） Can it be true? It cant be true.用于肯定句中，表示理论上的可能（有时候会）My sister can be really stubborn.This street can be rather crowded in rush hours.Anybody can make mistakes.4. 特殊句式can not / can never too或cannotenough “再也不过分，越越好”One cant be too careful. = One cant be careful enough.cant help doing / cant help but do禁不 住，不由得Hearing the funny story, I couldnt help laughing.Practice:2. The World Wide Web is sometimes jokingly called theWorld Wide Wait because it _ be very slow.A. Should B. must C. will D. canD1. An Englishman who _not speak Italian is now working in an Italian school.A. must B. can C. may D. mightB二、may 和might 1.表示请求或允许（可以）might比may语气更委婉。肯定回答用Yes, you may./Yes, please./Certainly./Sure, go ahead.1. 否定回答用No, you mustnt./No, youd better not.-May I ask you a question? -Yes, please./Sure, go ahead.-May I smoke here? -No, you mustnt./No, youd better not.2. （表示可能性）“可能，也许”只用于陈述句，不用于疑问句，might的 可能性比may小。may not表示“可能不”， cant 表示“不可能”What he said may / might be true.may / might not be true.cant / couldnt be true.May what he said be true?Can what he said be true?3. may 用于表示祝愿、希望、乞求等，主要用于 正式场合或书面语中。May+主语+动词原形May you succeed! 祝你成功! May your dream come true!愿你梦想成真！May God bless you! 愿上帝保佑你! 4. may / might as well 动词原形 “还是的好”You may / might as well go to see a doctor.5. 用于一些状语从句中（目的状语从句“以便，为了 ”；让步状语从句“即使，尽管，无论”）He got up early in order that he might catch the first bus.Try as he might, Im afraid he could hardly succeed.三、will 和would will 和would可表示说话者或主语的意愿，决心 ，意向 He would never give up. I will do all that I can to help you.2. will用于祈使句的反意疑问句中。Dont forget to close the door, will you? Go with me, will you?3. will表示现在习惯性的动作；would可表示过去的习惯动作，此时的意义接近used toThe old man will sit by the window for hours.He would sit there doing nothing.would与used to的区别：1）used to强调今昔对比（过去这样，现已不是 这样）；would只是回顾过去 2）would只能表示过去习惯性的动作，而used to 既可表示动作，也可表示状态4. 用于第二人称疑问句中，表示请求、建议或 询问对方意愿,would比will语气更委婉Would /Will you pass me the bottle? Would you like a cup of coffee?5. will可表客观事实、功能或属性。The door wont open.On Sundays, when I was a child, I used to / would get up early and do morning exercise. There used to be a supermarket near the hospital.1. 在疑问句中，用于第一、第三人称，用来征 询对方意见、请求指示或提出建议。四、shallWhat shall we do now? （征求对方意见）Mr. Smith wants to see you, manager. Shall he wait outside or in the office? （请求指示）It is a nice day. Shall we go out for a picnic?（提出建议）2. 用在第二、第三人称陈述句中，表示说 话人的“允诺、警告、命令、威胁、决心” 等语气。If you dare do that, you shall be punished.(警告，威胁）If you pass the college entrance examination, you shall get a computer.（允诺）Nothing shall stop us from carrying out this plan.（决心）3.应该,应当.用于条约，规定，规章等文件中 ，表示一种义务，多用于第三人称中。He shall have the right to own the house according to the law.（法律条文）-Can I pay the bill by check? -Sorry, sir. But its the management rules of our hotel that payment shall be made in cash. （规章制度）4. 用在 Lets do sth. 的反意疑问句中。Lets go swimming, shall we?思考：let us do 的反意疑问句Practice1. It has been announced that candidates (候选 人）_ remain in their seats until all the papers have been collected.A. can B. will C. may D. shall2. - The room is so dirty. _ we clean it?- Of course.A. Will B. Shall C. Would D. DoDB五、should 1. 表示义务或责任，建议或劝告，意为 “应该”You should keep your promise.Students shouldnt smoke.2. 表示推测 “按道理说应该会，想必会”（按照常识或以往的经验）You should be hungry after the long walk.The watch should be ready by 12:00.3. 表示说话人对某事不能理解，可翻译成“居然 ”，“竟然”，“竟会”，表示意外和出乎意料。It is surprising that he should have made such a foolish mistake.I m glad that your story should have won the first prize.4、表示语气较强的假设（用于条件句中） “万一”If the car should break down on the way, you would have to walk back.5. 用于表示命令、建议、要求的词后面，可省 略。He suggested that they (should) not waste time playing.Practice1.You can