人教必修三unit 语法情态动词.pptxVIP

Grammar;1. Ought to ;2. ought to 的否定句形式是oughtn’t to , 一般疑问形式是将ought 置于主语前. eg: We ought not to start so late. 3.在反意疑问句中常常省略to,用oughtn’t 或是shouldn’t.;You ought to have helped him with his English, ________ ? won’t you B. ought not you C. shouldn’t you D. wouldn’t you ; 2. have to;Have to 有多种时态。常见的有： 一般将来时 We will have to gather at the school gate at 7 tomorrow. 一般现在时 I have to take more money with me because my girlfriend has so much to buy. 一般过去时 Finally, we had to give up our idea to hold a picnic outside as it rained for a whole afternoon.; must表主观意志，而have to表由于客观因素不得不做完成的事情。 Must没有过去式，除在间接引语中可表示过去的时间。在直接引语中表示过去的时间用had to代替。 I told her that she must give up smoking. She said, “We had to get everything ready that night.”;即学即用:;3.他们没必要担心核辐射. They ________________the nuclear radiation. 4.我必须马上做吗? Must I do it at once ? No,______________________.;选词填空:must, mustn’t ,have to ;1. Johnny, you ______ play with the knife, you ______ hurt yourself. A. won’t ; can’t B. mustn’t ; may C. shouldn’t ; must D. can’t ; shouldn’t;2. --May I pick a flower in the garden? -- ________. A. No, you needn’t B. Not, please. C. No, you mustn’t D. No, you won’t;Need I do …? Yes, you must. No, you needn’t. ;注意对need问句的回答: --Need I finish the work today? --Yes, ________________. No, ________________. No, ________________.;1.You ______ return the book now. You can keep it till next week if you like. can’t B. mustn’t C. needn’t D. may not ;情态动词+have done 的用法;1.Must +have done 表示对过去发生的事情 作出的肯定判断;2.can/could have done 在否定句对过去 发生行为的可能性进行推测.;could(不用can)+have done,在肯定句中表示“本来能够…而没能…”，具有婉转的批评和责备之意,;3.might/may+have done;She might have been hit by a car or motocycle. 她可能是被一辆小气车或摩托车撞了。 The Jinsha Ruins may have been the political and cultural centre of the ancient Shu Kingdom. 金沙遗址可能是古代蜀国的政治和文化中心。;3.might+have done表示“本来可能…”，但实际上没有发生的事。另外，还可表示“本来应该或可以做某事”之意，含有轻微的责备语气。