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课件网) Unit 5 The Value of Money Part 3 Discovering Useful Structures Learning aims 1. To review the meanings and functions of some modal verbs; 2. To summarize the meanings of the two forms of past future tense; 3. To express modality and talk about future events Learning aims Grammar --modal verbs 一、定义：情态动词是一种本身有一定的词义，但要与动词原形一起使用，给谓语动词增添情态色彩，表示说话人对有关行为或事物的态度和看法，认为其可能、应该或必要等。 1. The characteristics of modal verbs A. They never change their form. You can't add "s", "ed", "ing"... 没有人称、数及时态的变化 They are always followed by an infinitive without "to" (e.i. the bare infinitive.) 后加动词原形 They are used to indicate modality and allow speakers to express adding meanings. 表达情感和态度 2. List of modal verbs （9） M M M W W C C S S ust ay ight ill ould an ould hall hould dare/need not/ought to/have to/ you’d better 3. Usage of modal verbs Modal verbs are used to express functions such as: 许可 能力 义务；责任 禁令 不必要 建议 可能性 概率 Permission Ability Obligation Prohibition Lack of necessity Advice possibility probability Page 54 Functions & Meanings Example Necessity Possibility 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. 义务，职责 必要，需要 may/might, could Mustn’t could have to Should; had better do Will do; be going to do 4. 相当于情态动词的: 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: 三、情态动词的分类 can/could, may/might, ought to, must need, dare/dared shall/should, will/would have to, used to 情态动词的用法 can & could (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 Explanation may & might 1. 表示请求或允许，译为“可以”。might语气较委婉 (但并非表示过去)。 I wonder if I might ask you a favor You may tell him this. 2. 表示推测, 译为“可能”。might比may所表示的可能性更小。 That may/might not be true. 3. may/might well (很可能); may/might as well (不妨，还 ... ...
