必修三 第二单元语法课件.pptVIP

情态动词 （2）Modal Verb 1. 情态动词表示推测 2.need 和dare 的用法 must +have done 表示对过去已经发生的行为进行肯定推测，意为“想必/准是/一定作了某事”。 1.We must have learned 2,000 words by the end of last term. 到上学期为止我们一定学了有两千个单词 。 2.He must have gone to Beijing. 他一定已经去北京了。 can/could+have done表示对过去的行为的怀疑和不肯定，通常用在否定句和疑问句中。 1. Can they have won the basketball match? 他们可能赢了篮球赛吗？ 2. It couldn’t have been Mr. Green. He has gone to Beijing. 那不可能是格林先生的，他已经去北京了。 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。 You could have told me earlier. 你本该早点告诉我的。 should/ought to+have done用于肯定句时，表示“本该做某事而实际上没做”，用于否定句时，则表示“本不该做某事却做了”。 You should have told him a week ago. 你本来应该在一周前告诉他的。 might（may）+have done表示 对过去发生的动作或存在的状态进行不肯定的推测。用于肯定句，意为“可能已经做过某事”；用于否定句，意为“可能没有做过某事”。might 的语气没有may肯定 She may have read the book. 他可能已经看过这本书了。 She might not have received your letter. 她或许没有收到你的短信。 needn’t +have done表示做了本来不必去做的事。 1.She needn’t have been to the station yesterday. 昨天她本不必到火车站去的.（昨天她去了） 2.You needn’t have bought it. 你本可不必买它的。 （你买了） 巩 固 练 习 1.Oh, I’m not feeling well in the stomach. I ____ so much fried chicken just now. A. shouldn’t eat B. shouldn’t have eaten C. mustn’t eat D. mustn’t have eaten 2.---Did you go to the movie the day before yesterday? ----No. We ___, but we decided not to. A.should have gone B. could go C. should go D. couldn’t have gone 哪两个是既可以做情态动词又可以做实意动词的？ need 和 dare 作实意动词时后面接带to 的动词不定式；作情态动词时后面接动词原形。 need 需要，必要 1. 用作情态动词，一般用于疑问句和否定句。 You needn’t come so early. Need I pay for it? 2. 用作实意动词时和一般的动词相同。有人称、数和时态的变化。 You need to have a good rest. She didn’t need to do so much housework. Do I need to hand in the homework now? need doing = need to be done 表示被动含义 Your clothes need washing. = Your clothes need to be washed. needn’t have done 表示过去本不必做某事却做了 didn’t need to do 表示 过去没必要做某事所以就没做 You needn’t have come yesterday. You didn’t need to come yesterday. dare 敢，敢于 用作情态动词，主要用于疑问句、否定句和条件句中。 I dare not say anything about it. How dare you talk li