1、 语法专题语法专题情态动词情态动词 情态动词框架图情态动词框架图 常见情态动词：常见情态动词： can/could; will/would; shall/should; may/might; need; dare; must; ought to, have to 情态动词情态动词 基本用法：肯定形式基本用法：肯定形式-情态动词情态动词 + 动词原形动词原形/ + be done/have done 否定形式：否定形式： 情态动词情态动词+not+ 动词原形动词原形 一一. 情态动词的基本用法情态动词的基本用法 (1) can、be able to 和和 could can 和 be able
2、to 都表示能力表示能力，意思上没多大区别。但 can 只有现在和过去时（could），而 be able to 则有更多的形式。但当成功地完成某一具体动作时，通常不用 could 而用 was/were able to 来表示。这时 was/were able to 相当于 managed to，表示经过一番努力，终于能够完成 某事。 例句： Can you use chopsticks? The wounded man still was able to get to the village and was saved in the end. can 和和 could can 和 coul
3、d 表示猜测，一般用于疑问句和否定句. 例句： -Can the news be true? - It cant be true. 表示请求、允许 （表请求时，口语中常用 could 代替 can 使语气更委婉，回答时用 can） 例子： Can I go now ? -Could I come to see you tomorrow? -Yes, you can. (否定回答可用 No, Im afraid not.) 表示惊异、怀疑、不相信的态度（主要用于否定句、疑问句或感叹句中） 例子： How can that be true? I cant believe my eyes and e
4、ars. How could you be so careless.? can 的特殊用法 Can but 只好 cant but 不得不 cant too 再.也不为过，越.越好 can not but do 表示“不得不/只好做” cant help but do 没有办法只有做 cant chose but do 没有选择只能做 can do nothing but do 只能做 have no choice but to do 别无选择而只有 例子： I can but wait. I cant but wait. You cant be too patient to the cust
5、omers. (2) may/might may/might 表示可能，但 may 比 might 可能性大。 Why isnt he in class? He may be sick.(生病的可能性较大) He might be sick.(生病的可能性较小) may/might 表示“请求、允许”，might 比 may 的语气更委婉一些。 may 用于现在时或将来 时，might 常用在间接引语中表过去时，但 might 也可用于现在时间，表示比较委婉的语气， 这个时候 might 不是 may 的过去时，回答用 may。 例句： -May I watch TV now ? -Yes,
6、you may. (Yes, please) -No, you mustnt. May / Might I use your bike? No, you mustnt/Im afraid not Yes, you can / may/Yes, please. may 可用于祈使句，表示祝愿。(不用 might) May we never forget each other. May you succeed! may/might as well 最好还是., 不妨； may/might well 很可能. 例句： You might as well do it now. He may well
7、be late for class. 练习： 用情态动词填空 1. It was so noisy that we _ hear ourselves speak. (couldnt) 2. The next day, Nicholas went out to look for help, but he _ find anyone. (couldnt) 3. You _feel all the training a waste of time, but Im a hundred percent sure later youll be grateful you did it. (may) 4. N
8、icholas _ (may) not have survived this snowstorm had it not been for TV. (might) （3）must must 表示必须，应该，没有时态变化。强调主观看法，只有现在时形式。 Must 开头的问 句，其否定回答要用 neednt 或 dont have to 来表达。 例子： We must do it now. -Must I hand in the paper today? -Yes, you need/must. -No, you neednt /dont have to. mustnt 表示禁止做某事,表示说话者
9、的命令或法律指令禁止，语气较强烈。 You mustnt smoke in the office. 还可以表示主语固执、偏要做他人不希望做的事 例子： It cant help; he must do that. （4）have to have to 表示“必须、不得不”，是由于某种外界（客观）原因而“必须”，“不得不”做某事，也 可表示经常的或习惯性的事“必须”做。have to 的否定形式表示不必。have to 可用于多种时态 中。 You will have to clean your own boots when you join the army. I have to be at
10、my office every evening. （5）ought to 表示义务和责任，意为表示义务和责任，意为“应该应该”, 比比 should 语气要强。语气要强。 例子：You ought to take care of yourself. 练习： 1. -Cant you stay a little longer? -Its getting late. I really _ go now. My daughter is home alone. (must) 2. You _be careful with the camera. It costs! (must) 3. You _be
11、Carol. You havent changed a bit after all these years. (must) （6）will / would Will 的用法的用法 will 用于各种人称表示“意志”、“意愿”或“决心”等，否定式 wont + 动词。 I will tell you all about it. Tom wont do such a thing. will 用于疑问句中，常用在第二称时(you)表示说话人向对方提出“请求”或“询问”。 Will you please tell her the news when you see her? Will you plea
12、se go with me? will 可用来叙述真理，表示目前习惯性动作或习惯，有“总是”、“惯于”的含义。通常用于 第三人称。 Fish will die out of water. She will listen to records alone in her room for hours . Would 的用法的用法 would 表示客气的请求、建议或意愿，比 will 更委婉，指现在时间，多用于第二人称。 Would you please be quiet? Would you like coffee? would 表示过去反复发生的动作或过去的习惯。如： When I passed
13、 my school I would see my teachers who taught me 5 years ago. We would play badminton on Sundays. （7）need need 作“必要”讲，既可作情态动词，也可作实义动词。 作情态动词后面直接跟动词原形 need + v 原形 例子： Need I come? 作实义动词时后面的动词不定式要带 to，sb. need(s) to do sth. I need to think it over. Need you go now? Yes, I must./No, I neednt need 表需要时，
14、可用 want, require 替换 sth need (s) to be done=sth need(s) doing sth. 例子： The desk needs repairing/ to be repaired. 练习： To become transparent, an animal _ (need) to keep its body from absorbing or scattering light. (needs) （8）dare dare 表示“敢”的意思。作为情态动词时，主要用在疑问句和否定句中。dare 若作实义动词， 在肯定句中要接 to, 在疑问句中和否定句中 t
15、o 可省去。 作为情态动词： How dare you say that? 作为实义动词： She doesnt date (to) ask her father. Do you dare (to) swim in the river ? He dares to catch a snake. （9）shall/ should Shall 的用法的用法 shall 作为情态动词用于第二、三人称，表示说话人的意愿，有“命令”、“警告、威胁、强制” 和“允许”等意思。 We shall do as our teacher says. You shall have the book as soon a
16、s I finish it. You shall be pubilished. 在疑问句中，shall 用于征求对方的意见或请求指示，常用于第一、第三人称。 Where shall he wait for us? Shall I come in ? Should 的用法的用法 表示责任、义务，意为应该。 You should listen to your doctors advice. 表示惊讶语气，意为“竟然” You should wear slippers in class. 用于条件句，表示假如，万一；省去 if , should 可提至句首。 Should you be late,
17、apologize to the teacher. 二二、“情态动词情态动词+have done”表示推测或判断的用法表示推测或判断的用法 (1) must have done 表示过去一定做过某事， 该结构只用于肯定句中 例子： She must have made a big mistake. (2) cant /couldnt have done 表示对过去事情的否定推测，译成不可能做过某事 例子： Mr. Smith cant have gone to Beijing , for I saw him in the library just now. (3) can have done
18、表示对过去行为的怀疑，用于疑问句， 译成“可能做过吗” 例子： There is nowhere to find him. Where can they have gone? (4) could have done 是虚拟语气，表示对过去事情的假设，表示本来能够做某事而没有做 例子： He could have passed the exam, but he was too careless. (5) may/might have done 表示对过去事情的推测。意思是可能已经或也许已经，用于肯定句 中。或者用于虚拟语气中表示本来应该/可以做某事（实际上未做） 例子： -what has ha
19、ppened to George? -I dont know. He may have got lost. 例子： You might have given him more help, but you were so busy. (6) would have done 用于虚拟语气中，表示对过去事情的假设，意思是本来会做,但实际做 了;wouldnt have done 本来不会做，但实际做了 例子： I would have told you all about the boys story, but you didnt ask me. (7) should have done 本应该做某
20、事而实际上未做； shouldnt have done 本不应该做某事而 实际上做了 例子： You should have told me about it earlier. You shouldnt have said such words to your parents. (8) ought to have done 本应该做某事而实际上未做， 而 ought not to have done 本不应该做某 事而实际上做了 例子： You ought to have told me about it earlier. You ought not to have said such wor
21、ds to your parents. (9) need have done 表示本来需要做某事而没有做； neednt have done 本来不需要做某事而 做了 例子： I neednt have bought so much wine-only five people came. 例子： He need have hurried to the station . In some case, he wouldnt have missed the train. 情态动词练习：情态动词练习： 单句语法填空 1. I cant find my purse. _ (leave) it in th
22、e supermarket yesterday, but Im not sure. (could/might have left) 2. I dont know where she is; she _ be in Wu han. (may) 3. The road is wet. It _ have rained last night. (must) 4. You _ be punished if you cheat in the exam. (shall) 5. Dont worry. Ive just sent an ambulance to you. They _ be there an
23、y second. (should) 6. I _ have gone to the school library, but it rained heavily, so I did not. (should) 单句改错 1. As a kid, I loved to watch cartoons, but no matter how many times I asked t watch them, my parents would not to let me. (省略 not) 2. Then he and my mother would have had a drink while she
24、prepared dinner and they would talk about his day and hers.(去掉 had) 3. Some classmates suggest we can go to places of interest nearby. (把 can 变为 should 或者省略) 4. We must found ways to protect our environment. （found 变为 find） 5. You had better not to have stayed there, but you did. (去掉 not) 6. My puni
25、shment lasted a year. Meanwhile, I found out that with more patience I must make my toys last. My attitude changed from then on. (把 must 改为 could /might) 7. I have been practicing for three weeks now, but I still couldnt get used to it-in fact, Ive nearly killed three people. (couldnt 变为 cant) 8. Thank you for all you have done for me. Mom, though I may often say it, I do love you. (may 后 面加 not) 9. Judging from what you said, he ought succeed. (ought 后面加 not)
