1、情态动词【知识要点】:情态动词（Modal verbs）本身有一定的词义，表示语气的单词。但是不能 独立作谓语，只能和动词原形一起构成谓语。情态动词用在行为动词前，表示说话人对这一动作或状态的 看法或主观设想。情态动词虽然数量不多，但用途广泛，主要有下列： can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) must not.情态动词无人称和数的变化，情态动词后面跟的动词须用原形，否定式构成是在情态动词后面加 “not“。疑问形式是将情态动词提至主语前。个别情态动词
2、有现在式和过去式两种形式，过去式用来表达更加客气，委婉的语气，时态性不强，可用于过去，现在或将来。情态动词属非及物动词，故没有被动语态。【典型例题】:【专题一】:can 和 could 的用法【例 1】Can you lift this heavy box?(体力)【解析】表示能力(体力、知识、技能)【练习】1.Mary speak three languages.(知识)2. you skate?(技能)此时可用 be able to 代替。Can 只有一般现在时和一般过去式 ;而 be able to则有更多的时态。Ill not be able to come this afternoo
3、n.当表示“经过努力才得以做成功某事”时应用 be able to,不能用 Can。【例 2】-Can I go now?- Yes, you can. / No, you cant.【解析】表示请求和允许。此时可与 may 互换。在疑问句中还可用could,might 代替,不是过去式,只是语气更委婉,不能用于肯定句和答语中。【练习】- I come to see you tomorrow?- Yes, you . -No, you /Im afraid not. 【例 3】Can this be true?【解析】表示推测(惊讶、怀疑、不相信的态度),用于疑问句、否定句和感叹句中。【练习】
4、This be done by him.How this be true?【专题二】may 和 might 的用法：【例 1】-Might/ May I smoke in this room?- No, you mustnt.【解析】表示请求和允许。might 比 may 语气更委婉,而不是过去式。否定回答时可用 cant 或 mustnt,表示“不可以,禁止”。用 May I.?征徇对方许可时比较正式和客气,而用 Can I.?在口语中更常见。【练习】- I take this book out of the room?- Yes, you . No, you 【例 2】May you su
5、cceed!【解析】用于祈使句,表示祝愿。【例 3】He may /might be very busy now.【解析】表示推测、可能性(不用于疑问句)。might 不是过去式,它所表示的可能性比 may 小。【练习】1.Your mother not know the truth.2.He very busy now.他现在可能很忙。【专题三】must 和 have to 的用法：【例 1】The man be our teacher。那个人一定是我们的老师。【例 2】 I study hard because of my dream .为了我的梦想我必须努力学习。【例 3】1.You c
6、ome in time.你必须准时过来【解析】：must 表示必须、必要。表示主观对事物的推测时，意为想必、一定，只用于肯定句中;表推测时，情态动词与动词原形(常为 be 动词)连用。而 have to 强调客观需要。【练习】:1.Her play is boring,I go now.2.Your mother be waiting for you now.3.I go home,because my father is ill.【例 4】-Must we hand in our exercise books today?-Yes,you -No,you 【解析】：在回答由 must 引出的
7、问句时，如果是否定的，不能用 mustnt,而用 neednt,dont have to.must 是说话人的主观看法,而 have to 则强调客观需要。【练习】:-Must he go to school now?-Yes,he -No,he .【专题四】should 及其否定式用法【例 1】：I should help her because she is in trouble.【解析】：should 表示应该、劝告、建议和命令。【练习】:1. You go to class right away.2. I open the window?【专题四】need 的用法【例 1】：You n
8、eednt come so early.【解析】need 作情态动词用时, 常用于疑问句、否定句。在肯定句中一般用must, have to, ought to, should 代替【练习】- Need I finish the work today?- Yes, you / No, you 【专题五】should 的用法【例 1】I should help her because she is in trouble.【解析】should 表示应该【练习】You take care of the baby.【例 2】You should go to class right away.【解析】表
9、示劝告、建议和命令。在疑问句中常用 should。【练习】 I open the window？【专题六】will 和 would 的用法【例 1】 I will do anything for you.【解析】表示询问，请求,将要。【练习】1. you pass me the book?2.She go to the library.【例 2】would you tell me the way to the school?【解析】表示过去的意愿或委婉提问自我检测(一)用适当的情态动词填空。1. Must I borrow the book with my ID card? No,you 2.
10、 I use your car? Yes, you 3. I go home now? No, you stay here and wait for the teacher.4.My mother is ill.I stay at home and look after her.5.I send an email to my friend.6. You take more exercise.7. you tell me how to get to the Park?8. We help each other.9. you like to go fishing with me?10. we pl
11、ay foot ball this afternoon?(二)按要求改写句子。1.I can run fast.(否定句)I fast.2.You must return the book now.(一般疑问句)I return the book now?No,you .3. He can play basketball well.(一般疑问句)He basketball well?4.They must take the books out of the room.(否定句)They the books out of the room.5.He will get up early.(否定句）
12、He get up early.(三)选择题。1. I told Sally how to get here, but perhaps I _ for her.A. had to write it out B. must have written it outC. should have written it ou D. ought to write it out2. There were already five people in the car but they managed to take me as well.It _ a comfortable journey.A. cant b
13、e B. shouldnt beC. mustnt have been D. couldnt have been3. Its nearly seven oclock. Jack _ be here at any moment.A. must B. need C. should D. can4. Johnny, you _ play with the knife, you _ hurt yourself.A. wont; cant B. mustnt; mayC. shouldnt; must D. cant; shouldnt5. The fire spread through the hot
14、el very quickly but everyone _ get out.A. had to B. would C. could D. was able to6. When can I come for the photos? I need them tomorrow afternoon.They _ be ready by 12:00.A. can B. should C. might D. need7. I stayed at a hotel while in New York.Oh, did you? You _ with Barbara.A. could have stayed B
15、. could stayC. would stay D. must have stayed8. Are you coming to Jeffs party?Im not sure. I _ go to the concert instead.A. must B. would C. should D. might9. I was really anxious about you. You _ home without a word.A. mustnt leave B. shouldnt have leftC. couldnt have left D. neednt leave10. Is Joh
16、n coming by train?He should, but he _ not. He likes driving his car.A. must B. can C. need D. may11. A left-luggage office is a place where bags _ be left for a short time, especially at a railway station.A. should B. can C. must D. will12. I wonder how he _ that to the teacher.A. dare to say B. dar
17、e sayingC. not dare say D. dared say13. When he was there, he _ go to that coffee shop at the corner after work every day.A. would B. should C. had better D. might14. It has been announced that candidates _ remain in their seats until all the papers have been collected.A. can B. will C. may D. shall
18、15. How _ you say that you really understand the whole story if you have covered only a part of the article?A. can B. must C. need D. may16. I hear youve got a set of valuable Australian coin. _ I have a look?Yes, certainly.A. Do B. May C. Shall D. Should答案解析(1)、1.neednt/dont have to 2.Can can 3. Ma
19、y must 4.have to 5. will 6.should 7.can/could 8. must/should 9.Would 10.can(二)1.Cant run 2.Must neednt 3. Can play 4.cant take 5.wouldnt(三)1. C。“ought to / should have+过去分词”表示后悔当初该做但却没做某事。“也许我本该把详细地址写给她的。”2. D。“couldnt have+过去分词”表示对过去情况的推测。既然小汽车上“已有五人”，且是“设法”才把你带去的，如此拥挤，旅途当然“不可能”舒服。3. C。nearly 暗示“时间
20、不早了”，Jack“按理应当(should)随时(at any moment)”都有可能到达这里。must 语气过强;can 一般不用于肯定推测;need 意义不通，也不用于肯定句。4. B。mustnt(不许、千万不)表示禁止。may 表示可能性。句意为“你千万不要玩刀子，可能会弄伤自己的”。5. D。表示过去具体某次“能够”做成某事只能用 was / were able to 而不用 could。6. B。should 表示按理应当，大概。can 一般不用于肯定推测;用 might 语气太不肯定，顾客可能走掉。7. A。could have done 表示本可以做但却没有做的事。句意为“你
21、本来可以住在 Barbara 那儿的”;而 must have done 只表示有把握的肯定推测，这与前面具有疑问语气的 Oh, did you?不符。8. D。语境明显提示“我可能(might)要去听音乐会” 。9. B。表示轻微的责备，句意为“我真的好担心你啊。你当时本不该不说一声就离开家的”。10. D。由“他自己喜欢开车”这一习惯推断，“他可能不会(may not)坐火车来”。can not“不可能”，语气太肯定。11. B。can 表示“可以”。should(应该), must(必须), will(愿意)均不符合语境。12. D。dare 作行为动词时,一般接 to do，但疑问式或否定式中 to 可以省略，此句有疑问口气。13. A。would 表示过去的习惯。14. D。在规章中告诫应考者，在收完所有试卷前“必须”留在教室里。15. A。can 在疑问句中，表示疑惑、怀疑，根据情况可译作“能、可以”等。16. B。may 表示请求对方允许，即：“我可以做吗?”
