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课件网) 情态动词 1. 情态动词的类型： 1) 只作情态动词的有：must, can (could), may (might), ought to 2) 可作情态动词也可作实义动词的有：need, dare 3) 可作情态动词也可作助动词的有：shall (should), will (would) 4) 具有情态动词的某些特征的有：have (had) to, used to 2. 情态动词的特征： 1) 有一定的词义，但不能单独作谓语，要和动词原形连用构成谓语。 2) 适用于主语的各种人称和数(have to例外，主语是第三人称单数时，要用has to)。 e.g. We / He must study hard. He has to walk home. 3) 后面接动词原形。 e.g. He may lose his way. 4) 具有助动词的作用，即可用来构成否定句、疑问句及用于简略答语。 e.g. —I can’t swim. Can you swim —Yes, I can. 1. can和could can/ could 用法 例句 can/ could can表示现在的能力，could表示过去的能力 Can you lift this heavy box Amy could sing English songs at the age of 4. 表示请求 、允许 。在一般疑问句中，could可代替can，但比can语气更委婉，回答时要用can —Could/Can you please do me a favor —Yes, I can. 情态动词基本语法功能: can/ could 用法 例句 can/ could can表示具体事情发生的可能，常用于否定句、疑问句，表示疑惑，惊讶或不相信等语气。 can表示理论上的可能时用于肯定句。 could表示推测时，可能性比can小，可用于肯定句、否定句和疑问句。 That can’t be Mary, for she is in hospital. (具体事情发生的可能性，表不相信) Accidents can happen in this weather. (理论上的可能性) It could be weeks before we get a reply. can/ could 用法 例句 can/ could can用于固定句型： can’t …too/enough (无论……也不为过)； can’t help doing sth. (禁不住做某事)； can’t help but do sth. (不得不做某事)； cannot /could not but do sth. (不得不做某事)； As a teacher, you can’t be too patient. 作为一名老师，你再耐心也不为过。 I could not but admire him. 我不得不佩服他。 2. may与might may/ might 用法 例句 may/ might may表示请求或允许，意为可以。 might 表示请求时语气更委婉。 might为may的过去式，常用于间接引语。 You may leave the book where it was. He might get there in time, but I can't be sure. She said I might call her at the weekend. (间接引语) may/ might 用法 例句 may/ might may表示推测，用于肯定句，意为“可能” may not 意为“可能不”若表达不可能用can’t She may be at home today. She may not be at home today. may表示祝愿,结构为：may+主语+动词原形 May you be happy forever! may/ might 用法 例句 may/ might 用于固定句型中： may/might as well do 不妨，还是做……为好；may/might well +do (=be likely to do) 有可能做…… So you might as well do what you love. Her appearance has changed so much that you might well not recognize her. 3. must与have to must 用法 例句 must 表示必要性，意为：必须 表示不必时用needn’t/ don’t have to。 You must finish your homework this afternoon. You don’t have to/ needn’t pay with cash. You can use a credit card. 其否定形式为mustn’t，意为“不许，禁止” You mustn’t smoke here. must 用法 例句 must 表示推测，一般用于肯定句，意为：一定，准是 She must be tired after such a long walk. 表坚持，意为：偏要，非要 Must you make her cry have to 用法 例句 have to 表示客观需要，意为:必须，不得不。强调客观上的 ... ...
