語(yǔ)法專(zhuān)題六：情態(tài)動(dòng)詞

1、語(yǔ)法專(zhuān)題六：情態(tài)動(dòng)詞1. 常見(jiàn)情態(tài)動(dòng)詞及用法說(shuō)明情態(tài)動(dòng)詞用法說(shuō)明can1) 表示主觀能力；2) 表示許可、請(qǐng)求；3) 表示可能性、推測(cè)，主要用于否定句、疑問(wèn)句中（肯定句中解釋為“有時(shí)候會(huì)”。習(xí)語(yǔ)：cant help doing；cant help but do(不能不、只能)could 為can的過(guò)去時(shí)，具備can的各種功能，語(yǔ)氣更委婉、客氣。注意：表示“征詢(xún)對(duì)方意見(jiàn)和允許”時(shí)，could 比can語(yǔ)氣委婉，但回答不用could。e.g.Can/could I smoke here? Yes, you can. / No, you cant.be able to1) 表示經(jīng)過(guò)一番努力之后做成某

2、事；2) 可用于各種時(shí)態(tài)。may1) 表示許可，允許；2) 表示可能性、推測(cè)；3) 表示祝愿（置于句首）；4) 其一般疑問(wèn)句的否定回答常用: No, cant. 習(xí)語(yǔ)：may well (not) do很（不）可能；may/might as well (not) do(最好，不妨)might為may的過(guò)去時(shí),具備may的各種功能,語(yǔ)氣更委婉,可能性更小。must1) 表示主觀上認(rèn)為“必須”，如為一般疑問(wèn)句，其肯定回答為：Yes,must.否定回答常為： No, neednt / not have to. 2) 表示“偏偏、偏要”；3) 表示肯定的推測(cè)或必然。have to1) 強(qiáng)調(diào)客觀上“不得

3、不”；2) 可用于各種時(shí)態(tài)。should1) 表示道義上的責(zé)任； 2) 表示意外、驚異； 3) 表示“按常理推斷理應(yīng)”；4) 用于 “Who should dobut”結(jié)構(gòu)中，表示“除了還有誰(shuí)會(huì)”。ought to與should同義，語(yǔ)氣略重；注意其疑問(wèn)式和否定式。shall1) 用于第一、三人稱(chēng)疑問(wèn)句，表示征求意見(jiàn)、請(qǐng)求；2) 用于第二、三人稱(chēng)陳述句，表示說(shuō)話者的意志、允諾、警告、命令、威脅等。3) 用在法律、條款、協(xié)定等文件中，表示義務(wù)、規(guī)定等。will1) 用于第二人稱(chēng)，表示征求意見(jiàn)、請(qǐng)求；2) 表示習(xí)慣性、傾向性；would則表示過(guò)去的習(xí)慣性、傾向性（*would只表示過(guò)去的習(xí)慣性、傾

4、向性，不涉及現(xiàn)在；used to 表示“過(guò)去常?！?，現(xiàn)在已不再）；3) 表示意志、決心；4) 表示意愿。would1）為will的過(guò)去式，表示請(qǐng)求時(shí)，語(yǔ)氣更委婉。2）表示過(guò)去的習(xí)慣性、傾向性。need“需要”的意思，常用于否定句、疑問(wèn)句中，無(wú)人稱(chēng)、時(shí)態(tài)變化，后接動(dòng)詞原形，否定式為neednt。dare“敢”的意思，常用于否定句、疑問(wèn)句中，無(wú)人稱(chēng)變化，但有時(shí)態(tài)變化，其過(guò)去式為dared, 否定式為dare/dared not, 后接動(dòng)詞原形。習(xí)語(yǔ)：I dare say 我想，我認(rèn)為2. 情態(tài)動(dòng)詞表示推測(cè) 1)可能性由大到小順序排列：must（肯）can（否/疑）could（肯/否/疑）may（肯

5、/否）might(肯/否) 2)對(duì)已經(jīng)過(guò)去的情況推測(cè)，用“情態(tài)動(dòng)詞+have done”結(jié)構(gòu) must have done 肯定已經(jīng)做了 cant/couldnt have done 不可能已經(jīng)做了. may/might have done 可能已經(jīng)做了 neednt have done 本不必做. could have done = 1 * GB3 本能夠做. = 2 * GB3 可能已經(jīng)做了 (在肯定句中，不可用can) should have done/ought to have done 本該做 shouldnt have done/oughtnt to have done 本不該做

6、注意：以上句子的反義疑問(wèn)句要根據(jù)該句的實(shí)際時(shí)態(tài)來(lái)定。鞏固練習(xí)：1. Ding Junhui _ the championship; He didnt pass the first round.A. might not have won B. shouldnt have won C. couldnt have won D. mustnt have won 2. Children under 12 years of age in that country _ be under adult supervision when in a public library.A. must B. may C.

7、can D. need3. I am sure youd rather he stayed in Spain, _? A. wouldnt you B. arent I C. didnt he D. hadnt you4. -Could I borrow your pencil? -Of course, you _.A. can B. may C. could D. might5. You _ to the meeting this morning if you have something important to do. A. neednt to come B. dont need com

8、eC. dont need coming D. neednt come6. I promised to get there before 5 oclock, but now the rain is pouring down. They _ for me impatiently. A. may wait B. ought to wait C. could wait D. must be waiting7. Ive decided to take the job and I _ change my mind. A. mustnt B. cant C. wont D. may not8. I _ u

9、p early this morning. So I stayed in bed till 9 a. m.A. neednt have got B. didnt need to getC. shouldnt have got D. cant have got9. The flower is dead. I _ it more water.A. will give B. would have givenC. must give D. should have given10. It is natural a man as old as he _ be very forgetful. A. can

10、B. must C. should D. would11. The dog barked fiercely, but no one _ over to stop it.A. could go B. dare goC. dared go D. might go12. We _ hurry if we want to arrive in time.A. must B. needC. may D. have to13. He _ get up early when he lived in the countryside.A. would B. will C. mustnt D. cant14. _

11、you please pass on a message to him?A. Do B. ShallC. May D. Will15. -Could I call you by the first name? -Yes, you _.A . will B. could C. may D. might16. The fire spread through the hotel very quickly but everyone _ get out. A. had to B. would C. was able to D. could17. Its nearly seven oclock. Jack _ be here at any moment. A. must B. need C. should D. can18. -I think Helen is at home.- No, she _ be at home, for she phoned me from the airport just five minutes ago.A. mustnt B. needntC. cant D. darent19.Hes late. What _ have happened to him?A. can B. mayC. should D. must20. Af