情态动词must, can, could, may, might表推测的用法：情态动词中的must, can, could, may, might都表推测其中must的可能性最大，can / could次之，may / might最小具体用法如下：表示推测的情态动词有must, could, may, might, can, should等情态动词+动词原形” 表示对现在或将来的推测，“情态动词+动词进行式（v-ing）”表示对正在进行的动作或事情的推测，“情态动词+动词完成式（have done）”表示对过去的推测其反意疑问句中，疑问部分的助动词由情态动词后的助动词决定1. must的用法（1）表示推测“可能性”时，意思是“一定、准是”，语气较肯定，较有把握 He must be American. = It is certain that he is American. 他准是个美国人2）must表推测只能用于肯定句如果要表示“一定不、肯定不”的意思时，应用can`t, 如询问某种可能时（疑问句），应用can He must know my address. 他肯定知道我的地址。
一定） He can`t know my address. 他肯定不知道我的地址一定不） Can he know my address? 他知道我的地址吗？（询问可能性）（3）must表示推测时，可以推测现在/正在发生的动作/过去发生的动作 He must have a car now. （现在）他一定有辆小汽车 He must be doing his exercises in the classroom.（正在进行）他一定在教室里做练习 He must have finished the work.（过去发生）他一定已完成了工作 注：must表示推测时很少用于将来的情况2. can / could的用法（1）can表示推测“可能性”时，往往用于否定句或疑问句Can`t“一定不”，语气很肯定 can在疑问句中意思是“会、可能” He can`t be at home. = It is impossible that he is at home. 他一定不在家2）can /can`t后可接进行时/完成时，表示对现在发生的动作或过去发生的动作进行推测。
They can`t be reading in the library. 他们一定不在图书馆读书对现在发生的动作推测） He can`t have gone to Shanghai for I saw him a minute ago. （对过去推测） 他不可能去了上海，我刚才还看见他 It`s so late. Where can she have gone? 天晚了，她可能去哪儿了呢？（3）could可用于表示某事有可能发生或可能是事实可能” Don`t eat it. It could be poisonous. 不要吃它，可能有毒 The plane could be delayed by fog. 飞机可能会因为雾晚点 （4） could还可以用于表示客气、委婉、礼貌的请求语气 Excuse me, could you tell me the way to the bus station? Could you help me?（5）couldn`t表示否定推测，表示某事不可能真实，或由于特定事实或环境某事肯定不会发生。
It couldn`t possibly be poison. 这不可能是毒药注：有时与形容词的比较级连用强调某人或某物不可能再更多地具有某种属性 You couldn`t be more wrong. 你真是大错特错 I couldn`t be happier. 我简直是幸福极了3. may和might的用法（1） may, might表示推测“可能性”时，意思是“可能”、“也许”，语气没有 must肯定 He may / might be American. = It is possible that he is American. 他可能是个美国人 注：might不表示过去时态，只是语气上比may更委婉，表示的可能性更小2）may, might表推测时，可以用于否定句，意思是“可能不、也许不”，但不用于疑问句 He may / might not be at home. 他也许不在家3）may, might可以推测现在正在发生的动作或过去发生的动作或将来的情况 He may / might be sleeping now. （现在）他可能正在睡觉。
The boy may / might not be watching TV at home. （现在） 这个男孩可能没在家看电视 These students may / might have seen the film before.（过去） 这些学生以前可能看过这部电影 I think we should take raincoat with us, it may rain. （将来） 我想我们应该带上雨衣，可能要下雨了 She might not come this afternoon. 她今天下午可能不来了将来）4. 其反意疑问句中，疑问部分的助动词由情态动词后的助动词决定 He must be a worker, isn`t he? （现在）他准时个工人，是吗？ It must have rained last night, didn`t it? （过去）昨晚一定下雨了，是不是？ You must have learned English for many years, haven`t you? （完成时） 你一定学了好多年英语，是吗？练习题1 John___ come to see us tonight, but he isn't very sure yet. A. may B. need C. can’t D. must 2 John isn’t in the classroom. He play soccer on the playground with Bob. A. can B. must C. should D. can’t3 -Will you go to the cinema with us? -No, I rather read a magazine at home. A. should B. might C. would D. had better4 You___ go and see a doctor at once because you got a fever. A. can B. must C. dare D. would5 -Can you speak Japanese? -No, I____. A. mustn't B. can't C. needn't D. may not 6 -He___ be in the classroom, I think. -No, he ___ be in the classroom. I saw him go home a minute ago. A. can; may not B. must; may not C. may; can't D. may; mustn't 7 -Is Lena swimming in the pool? -No, she swim. She is terrified of water.A. may not B. must not C. can't D. needn't8 He isn't at school. I think he ___ be ill.A. can B. shall C. must D. might9 -What do you think “upset” means? - I’m not sure. It mean “sad”.A. may B. must C. can D. should 10 The children___ play football on the road. A. can't B. can C. mustn't D. must 11--Are you coming to Jeff’s party? (NMET 2000) --I’m not sure.I_____go to the concert instead. A.must B.would C.should D.might 二、根据句子意思用must, might, could或can’t填空1. The white ruler belong to Lucy. Hers is red.2. I can’t find my keys. They be still at home.3. Jim be at home. He has gone to his hometown.4. The schoolbag be Paul’s. There are a lot of books in it.5. The classroom is clean. Someone clean it just now.6. –Is that Bob there? –No, it be him. He has gone to Shanghai with his family7. –where is Mr. Lee? –The light in his bedroom is still on. He be there.8. I find my pencil case. I think I have lost it.9. The boy is clever. He tell many stories when he was young.10. I have tried to call him at the office, but there is no reply. He be at home. 情态动词用法 （结构：情态动词+动词原形）1）must ①表义务，必要性：应该，必须（常用于肯定句和。