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课件网) Unit 5 The Value of Money Discovering Useful Structures P54 Modal verbs 情态动词 Leading-in May we ask what you're doing in this country and what your plans are I can't say that I have any plans. You mustn't worry about that. Could you offer me work here Read the sentences below and think about: What are the functions and meanings of these modal verbs A. necessity B. possibility C. obligation D. request E. advice F. intention 一、情态动词的特征 情态动词有一定的意义，表示或暗示某种情绪或态度，表示可能、建议、愿望、必要、允许、能力等。 大多数情态动词有多个意义。 2. 情态动词没有人称和数的变化，即不随主语的不同而变化。 3. 情态动词不能独立使用，须后接动词原形，一起构成谓语动词。 4. 情态动词除ought和have外，后面接不带to的不定式。(dare) 5.情态动词没有非谓语形式，即没有不定式、分词等形式。 1.只作情态动词的： 2. 可情态可实义的： 3. 可情态可助动词的: 4. 相当于情态动词的: 二、情态动词的分类 can/could, may/might, ought to, must need, dare shall/should, will/would have to, used to Example Necessity Possibilities Obligation Request Advice Intention We can discuss it now. You must do it at once. Would you please pass me the salt You needn’t have stayed. You ought to help him. I would rather do it myself. can & could 情态动词的用法 (1) 表能力，“能，会” She can speak English. She could play the piano at the age of three. be able to能用于各种时态；can/could只能表示现在或过去的能力。was/were able to“设法做成某事”相当于managed to do sth// succeeded in doing sth All the people trapped in the burning house were able to get out of it. (2) 表请求和许可，“可以”，could比can更加委婉，表示礼貌 Can I smoke here —Could I use your computer —Yes, you can. (3) can表客观可能性，“有时候会”，用于肯定句 A wise man can sometimes make a mistake. (4) can表推测，用于疑问句、否定句。肯定句用must Can the news be true He can’t be at home because I saw him here just now. can/could与be able to的区别 1. The man can/could speak two foreign languages. 2. Yesterday I was able to get home before the heavy rain. can/could表示_____，而be able to通常表示通过努力达成的_____; can/could 主要是一般现在、一般过去时, 而be able to有较为丰富的时态变化。 习惯性具备的能力 一次性的能力 may 和 might May I have a look at your book You may use may dictionary so long as you return it before 7:00. He may be waiting for you at the station. They may have got lost. 可能性 许可 请求 may/might have done 过去的猜测 当句中出现 “I am not sure” 等表示不确定含义的时候,常选用may 和might . I ___( may/can) go, but I am not quite sure. 可能性： can > could > may > might 1. 对may的一般疑问句的肯定回答可用may或can, 但作否定回答时要用mustn't或can't。 —May (Might) I have a little brandy —No, you mustn't. You'd better not. 2. May可以表示祝愿或希望，而might不行。 May they be very happy in the future. May you succeed in the coming year. shall & should & ought to shall shall用于第一、三人称疑问句中，表示说话人征求对方的意见和向对方请示，“…好吗？要不要…？ ... ...
