情态动 情态动词( model verb)用来表示能力 允许、可能、必须、劝告、意愿等概念或态 度。主要的情态动词有can( could),may (might), shall (should), will (would) must, ought to,need,dare等。情态动词没有 人称和数的变化,其后常跟不带to的不定式
情态动词 情态动词（model verb）用来表示能力、 允许、可能、必须、劝告、意愿等概念或态 度。主要的情态动词有can （could），may （might），shall （should），will （would）， must，ought to，need，dare等。情态动词没有 人称和数的变化，其后常跟不带to的不定式
1.情态动词的一般用法: ●(1)表示能力:can, could, be able to o he is over 80 but still can read without glasses She couldn't come yesterday ● He can' t come tomorrow
1. 情态动词的一般用法： ⚫ (1) 表示能力: can, could, be able to ⚫ He is over 80 but still can read without glasses. ⚫ She couldn't come yesterday. ⚫ He can’t come tomorrow
●can/ could与 be able to用法比较 ) be able to除有一般现在时、一般过去时、一般将来 时外,还可有现在完成时、不定式、动词-ng形式等。 o This is the information Ive been able to get so far To be able to ride a bike, she practiced a lot Just being able to drive a horse, a cart isnt much help to 2) could表示过去总的、经常性的能力 was/were able to表示过去具体情况下具有的能力,并且做了某动作。 He could speak French. so he was able to show the French lady the way ●3)表示将来的能力常用 will be able to When will you be able to take us to town?
⚫ ⚫ can/could 与be able to 用法比较 ⚫ 1）be able to 除有一般现在时、一般过去时、一般将来 时外，还可有现在完成时、不定式、动词-ing 形式等。 ⚫ This is the information I’ve been able to get so far. ⚫ To be able to ride a bike, she practiced a lot. ⚫ Just being able to drive a horse, a cart isn’t much help to us. ⚫ 2) could表示过去总的、经常性的能力；was/were able to 表示过去具体情况下具有的能力，并且做了某动作。 ⚫ He could speak French, so he was able to show the French lady the way. ⚫ 3) 表示将来的能力常用will be able to. ⚫ When will you be able to take us to town?
(2)表示许可: can/could, may/might;cant,may not. mustnt. must not ●1)征询“许可”或给予“许可”可用 can/could或 may/might表示 May用于正式场合,can用于非正式场合, could用于客气的询问 might极少用。 You can go at four o'clock Could i borrow your pen? Students may take 3 books each o Might I ask whether you are using the typewriter? ●2)表示“不允许”用cant, may not, mustn t; must not语气重。 You cant leave the table unless you finish your meal Put that cigarette out. You must not smoke near a petrol pump 3)表示过去“许可”不用 could, might,要用其他表达方式 We had been/were given permission to speak to the patient 但在间接引语中表达过去“许可”,可用 could, might The nurse said that we could/might speak to the patient for just a few minutes
(2) 表示许可：can/could, may/might; can’t, may not, mustn’t, must not ⚫ 1) 征询“许可”或给予“许可”可用can/could 或may/might 表示。 May 用于正式场合，can 用于非正式场合，could 用于客气的询问， might 极少用。 ⚫ You can go at four o’clock. ⚫ Could I borrow your pen? ⚫ Students may take 3 books each. ⚫ Might I ask whether you are using the typewriter? ⚫ 2) 表示“不允许”用 can’t, may not, mustn’t； must not 语气重。 ⚫ You can’t leave the table unless you finish your meal. ⚫ Put that cigarette out. You must not smoke near a petrol pump! ⚫ 3) 表示过去“许可”不用could，might，要用其他表达方式。 ⚫ We had been/were given permission to speak to the patient. ⚫ 但在间接引语中表达过去“许可” ，可用could，might。 ⚫ The nurse said that we could/might speak to the patient for just a few minutes
3)表示可能性:may/ might,can/ could,must can t 1)may,migt用来推测现在“可能”;may比 might表示的可 能性大些。 o Why isnt John in class? He may/might be sick ● maybe是副词,不是情态动词。 Maybe he ●2)在日常口语中常用 can/could表示“可能” o You can/could walk for miles in the country without meeting anyone e Can the news be true? No it cant be true ●3)mus表示可能性最大,“必定”;否定形式用can?t表示 肯定不”、“必定不会” o You must be hungry after a long walk o The phone is ringing, but there is no answer. She cant be at home
(3) 表示可能性：may/might, can/could, must; can’t ⚫ 1）may, might 用来推测现在“可能” ；may比might表示的可 能性大些。 ⚫ Why isn’t John in class? He may/might be sick. ⚫ maybe是副词，不是情态动词。Maybe he is sick. ⚫ 2) 在日常口语中常用can/could 表示“可能” 。 ⚫ You can/could walk for miles in the country without meeting anyone. ⚫ Can the news be true? No, it can’t be true. ⚫ 3) must表示可能性最大， “必定”；否定形式用can’t表示 “肯定不” 、 “必定不会” 。 ⚫ You must be hungry after a long walk. ⚫ The phone is ringing, but there is no answer. She can’t be at home
(4)表示必须和需要:must, have to,need 1)mus表示说话人认为“必须”;否定回答 时用 needn?t“不必”。 You must be here at nine o'clock o Must you go soon? No, I neednt go yet ●2) have to表示他人或客观情况要求“必须”。 o I have to be back at school by eight. I have a lot of work to do tonight We don ' t have to wear uniforms in school ●口语中常用 have got to表示“必须 oI have got to leave now. i have a meeting in ten minutes
（4）表示必须和需要：must, have to, need ⚫ 1）must表示说话人认为“必须”；否定回答 时用needn’t “不必” 。 ⚫ You must be here at nine o’clock. ⚫ Must you go soon? No, I needn’t go yet. ⚫ 2) have to 表示他人或客观情况要求“必须” 。 ⚫ I have to be back at school by eight. I have a lot of work to do tonight. ⚫ We don’t have to wear uniforms in school. ⚫ ⚫ 口语中常用have got to 表示“必须” 。 ⚫ I have got to leave now. I have a meeting in ten minutes
3)need表示动作者“需要”、“有必 要”,用于否定句或疑问句;肯定回答 用must,否定回答用 needn't。 Need he go now? Yes, he must. No he neednt need常用作实义动词。 o You need to learn the value of time o You didn 't need to tell him the news ● Does she need to go
⚫ 3) need 表示动作者“需要” 、 “有必 要” ，用于否定句或疑问句；肯定回答 用must，否定回答用needn’t。 ⚫ Need he go now? Yes, he must. No he needn’t. ⚫ ⚫ need 常用作实义动词。 ⚫ You need to learn the value of time. ⚫ You didn’t need to tell him the news. ⚫ Does she need to go? ⚫
(5)表示责任和劝告: should, ought to,must, had better ●1)用 should和 ought to表示责任和劝告,后者的 语气重些 o You should/ought to do as you are told o Such things shouldn ' t/ought not to be allowed ●2)有时也用mus表示责任和劝告。 o You must see the movie. It's wonderful ●3)口语中也常用 had better表示劝告,意为“最 好做/不做某事”。 o You had better take care of yourself. You d better not make a mistake next time o hadnt you better see who is at the door?
（5）表示责任和劝告: should, ought to, must, had better ⚫ 1) 用should和ought to 表示责任和劝告，后者的 语气重些 ⚫ You should/ought to do as you are told. ⚫ Such things shouldn't/ought not to be allowed. ⚫ 2) 有时也用must 表示责任和劝告。 ⚫ You must see the movie. It’s wonderful. ⚫ 3) 口语中也常用had better 表示劝告，意为“最 好做/不做某事” 。 ⚫ You had better take care of yourself. ⚫ You’d better not make a mistake next time. ⚫ Hadn’t you better see who is at the door?
(6)表示建议:sha, may/might as well may/might just as well ●1)“shll/we..”表示征求对方对建议的看法。 o Shall we carry the boxes into the house? ● Lets go, shall we ●2)may/ might as well, may/ might just as well表 示推荐更住方案,建议另一种做法,意为“倒 不如 不也一样吗?” o We may as well stay here tonight o You might just as well tell the truth
（6）表示建议：shall，may/might as well, may/might just as well ⚫ 1) “shall I/we…” 表示征求对方对建议的看法。 ⚫ Shall we carry the boxes into the house? ⚫ Let’s go, shall we? ⚫ 2) may/might as well, may/might just as well 表 示推荐更佳方案，建议另一种做法，意为“倒 不如……” ， “……不也一样吗？” 。 ⚫ We may as well stay here tonight. ⚫ You might just as well tell the truth
(7)表示许诺: shall ●shal)于第二、三人称,表示说话 人的许诺。 You shall have your money back next week If he passes the exam, he shall have a holiday
(7) 表示许诺：shall ⚫ shall用于第二、三人称，表示说话 人的许诺。 ⚫ You shall have your money back next week. ⚫ If he passes the exam, he shall have a holiday