高三英语复习-情态动词课件
Grammar,Modal verbs,情态动词(一),情态动词主要表达说话人的看法、态度 等。从用法上来说,有这样几个特点: 一是情态动词自身都有一定的意义, 但不能表示正在发生或已经发生的 事情,只表示期待或估计某事发生。 二是情态动词除ought和have外,后 面必须接不带to的不定式。 三是情态动词没有人称和数的变化, 也没有非谓语形式。,只作情态动词的: can/could, may/might, ought to, must 可情态可实义的: need, dare/dared 可情态可助动词的: shall/should, will/would 相当于情态动词的: have to, used to,1. must, cant 1) must 表示必须、必要, must表示主观多一些 而have to则表示客观多一些。回答must引出 的问句时, 如果是否定的回答, 不能用mustnt, 而要用neednt或dont have to。如: Must we hand in our exercise books today? Yes, you must. (No, you dont have to.) 2) cant在口语中代替mustnt时,表示禁止 或不准。如: You cant play football in the street.,3) must 表示推测时, 只能用于肯定句。 There must be something wrong with the computer. 这个电脑肯定出了问题。 You have worked hard all day. You must be tired.你努力学了一整天了,一定累了吧。 4) must +be doing/do 表示对现在的动作进行 肯定推测。如: 他现在一定在看小说。 He must be reading novels now. They have bought a new car. They must have a lot of money. 他们买了一辆新车, 他们一定很有钱。,5) must +have done 表示对过去发生的事情 作出的肯定判断。 他们在玩篮球,他们一定已经完成了作业。 They are playing basketball, they must have finished their homework. 路是湿的, 昨天晚上一定下雨了。 The road is wet. It must have rained last night.,2. can, could 1) can /could 表示推测时, 只能用在否定句 或疑问句中。 Its so late. Can Tom be reading? 这么晚了, 汤姆还在看书吗? It cant be Mary. She has fallen ill. 这个人不可能是玛丽, 她生病了。 She couldnt be telling lies. 她不可能在说谎。,2) can/could have done 对过去发生行为的可能 性进行推测: 刚才我还看见他了,所以他不可能出国的。 I saw him just now so he couldnt have gone abroad. 门是锁着的,所以她不可能在家。 The door was locked. She couldnt have been at home.,3) can/could have done “本可以, 本来可能 已经” 用于肯定句中, 表示对过去发生的事情做出 的判断。 你本来可以考的更好。 You could have had a better mark.,3. may/might 1) may/might表示推测时, 只能用于陈述句, 表示对现在或将来要发生的动作把握不大。 她们明天可能会到这里来。 They may come here tomorrow.,他们可能还在等我们呢。 They may be still waiting for us. 2) might 可用于指过去的行为或者表示可能性 更小。 他也许在作功课吧。 He might be doing his homework now. 我问他我是否可以离开。 I asked him if I might leave. I asked him “May I leave now?”,3) might/may have done, 表示对过去发生的动作 进行可能性推测。 他可能去医务室了。 He may have gone to the clinic. 他可能已经从报纸上知道这个消息了。 He might have read about the news in the newspaper.,Will /Would you do? 表请求, 意志, 愿望, 决心。 would 表过去反复发生的动作或某种倾向 “总是,总要” used to 表过去常常(现在已没有这种习惯) “过去常常” used to 可与状态动词连用, would不可以 e.g. He used to be a quiet boy. () He would be a quiet boy. ( ),4. will/would,1) 表示请求、建议等, would比will委婉 客气。 Would you pass me the book? 2) 表示意志、愿望和决心。如: I will never do that again. They asked if we would do that again.,5. shall, should 1) 在一、三人称的疑问句中, shall用来 询问对方的意愿。如: Shall we begin our lesson? When shall he be able to leave the hospital? 2) 用于二、三人称的陈述句中, 表说话人 命令、警告、允诺等口吻。如:,He shall have the book when I finish reading. You shall do as I say. 3) should表示劝告、建议、命令, 其同义 词是 ought to; 在疑问句中, 通常用 should 代替 ought to。如: You should go to class right away.,4) should/ought to have done 过去应该 做的事情而没有做, 表责备。如: You should have written with a pen, not a pencil. Yes, I know I ought to have, but I had no pen to write with.,5) should / ought not to have done 过去不应该做的事情却做了, 表责备、 悔恨情感。如: I was really anxious about you. You shouldnt have left home without a word.,Im not feeling well in the stomach, I shouldnt have eaten so much fried chicken just now. 6) neednt have done 过去本不必做的 事情实际上却做了。如: You neednt have told him that.,1. When you are very sure of something, you use must in positive sentences and cannot or cant in negative sentences.,e.g. You must be Jeanne. Im Mathilde Loisel. We used to know each other very well. It cant be true! I dont believe it.,2. When you are quite sure about something, you use can.,e.g. Attending a ball can be exciting.,Practice 1,3. When you think that something is possible, but you are not very sure, you use could, may or might.,e.g.You could borrow some jewellery from your friend Jeanne, who is married to a rich man. You may not know that the necklace I returned is not the one that I had borrowed. Dont you have a friend who might lend you some jewellery?,Practice 2:表示推测情态动词的重要用法,1. You must be Mr Smith-I was told to expect you here. 2. He must have known what we wanted. 3. We may have read the same report. 4. He cant have slept through all that noise. 5. Theres someone outside-who can it be? 6. What can they be doing? 7. These pills might help to cure your disease. 8. You could be right, I suppose.,表示推测情态动词的重要用法,肯定的推测 可能的推测 否定的推测 疑问的推测,must,对将来 对现在 对过去,情态动词,may, might,cant, couldnt,can, could,+ V. + V. + have done 常见must be + be doing,+ V. + V. + have done + be doing 可以用not表示“可能不”,+V. + V. + have done + be doing,+ V. + V. + have done + be doing,1. I dont know where she is, she _ be in Wuhan. 2. At this moment, our teacher _ our exam papers. 这时, 我们老师想必在批改试卷。 3. The road is wet. It _ last night. (rain) 4. Your mother _ for you. 你妈妈一定一直在找你。,may,must be marking,must have rained,must have been looking,Practice 3: Fill in the blanks.,5. Philip _ seriously in the car accident.