情态动词

情态动词:情态动词本身有一定的含义,但不能单独作为句子的谓语,必须后面紧跟动词原形(除ought). 情态动词没有人称和数的变化． 初中阶段我们主要掌握：can(could), may(might), must, need, would, should, ought等． １．表示能力 can/could (现在时／过去时） I can sing English songs. Can you sing English songs? I could sing English songs at the age of five. 注意：can 和 be able to 的区别 １．Be able to 可用于各种时态 We have been able to talk in English. They will soon be able to talk in English. 2. was/were able to 表示过去一次性设法作成某事． 反意词：fail to do The man was able to run away.=The man ________ _______ run away. =The man _________ _____ running awy. managed to succeeded in

2. 表示许可 表示对过去的推测 Can I take a seat here? 自强而弱 May I take a seat here? Could I borrow your bicycle? 自强而弱 肯定回答　　　　　　　　　　否定回答 Can? May? Could? Yes, you can. No, you can’t. Yes, you may/can. No, you mustn’t/can’t/may not. Sure./OK./… I’m afraid you couldn’t. Because… May be (可能是）　must be (一定是) Mustn’t be (不一定是）　can’t be (一定不是） 3. 表示猜测 Look, the light is off in the room. Danny must have got to bed. (must be in bed) 表示对过去的推测 情态动词＋现在完成时

语气委婉，从句不进级 …don’t we? Could 和might 的用法 （１）．是can和may的过去时 （２）. 特殊性 Could you tell me whether they will come here tomorrow? He may arrive soon. Let’s set the table. He might come this afternoon. I’m not sure. 比may的语气更不肯定 ４. 表示必须　　　must You must say sorry to your teacher. You mustn’t smoke here. Must we finish homework now? Yes, you must./No, you needn’t=No, you don’t have to. Must规章制度 Have to客观条件逼迫 Must和have to do 的区别 My mother is ill. I have to look after her at home. It is raining hard. We have to take a taxi. …don’t we?

Need作情态动词时，多用于否定或疑问结构，一般不用于肯定句，表示“必要”。 needs He ______ money now. (need) ______ she ______ to bring the book here? (need) They ______ go to work that day.(not need) The boy ________ any help.(not need) Does need needn’t/didn’t need to doesn’t need 没有必要 needn’t =don’t need to=don’t have to May…? Must…? Need…? No, sb. can’t/may not/mustn’t. No, sb. needn’t/don’t have to. Yes, sb. must. No, sb. needn’t.

6. 表示责任 should, ought to (应该) You had better work hard at all your subjects. =You _______ work hard at all your subjects.=You _____ ______ work hard at all you subjects. should ought to shouldn’t, oughtn’t to 7. Would作为情态动词，多于请求。 Will/Would you please sing us a song? Would you like a cup of tea? Would you like to join us for dinner? Would you mind our having a party in this room?=Would you mind if we have a party in this room? I would like to do / I would prefer to do / I would rather do / I would be interested to do

在反意疑问句中的运用 You must say something at the meeting (否定句) You _______ say ______ at the meeting. You must say something at the meeting. (反意疑问句) You must say something at the meeting, _______ _______? He had to finish his homework yesterday. (反意疑问句) He had to finish his homework yesterday, ________ _______? needn’t anything mustn’t you didn’t he didn’t there There used to be a dirty river here, _______ _______? You’d better not smoke any longer, ______ ______? Kitty failed to get an A for her maths test., _______ _______? He’d rather stay at home, ________ _______? had you didn’t she would he