1、Grammar,Modal verbs 情态动词,情态动词的语法特征,1） 情态动词 不能单独做谓语，它与其他动词构成谓语时，总是放在其他动词之前。,3） 情态动词没有人称，数的变化，但有些情态动词，如can、will也有一般式和过去式的变化。,4） 情态动词的“时态”形式并不是时间区别的主要标志，不少情况下，情态动词的现在式形式和过去式形式都可用来表示现在时间、过去时间和将来时间。,2）除ought 和have 外，后面只能接不带to 的不定式。,1) Some of us can use the computer now,but we couldnt last year. 2) The n
2、ew-built theatre can seat 1500 people.3) Can she be in the computer center? 4) I though what he said could not be true. can在肯定句中表可能性时，表示理论上的可能性。 Even expert can make mistakes. He can be very friendly at times.“有时候会”5) Can/Could I use your dictionary? 6) Could you lend me a hand?,1.表能力,3. 表示“请求” “允许”
3、(表请求时，口语中常用could 代替 can 使语气更委婉，回答时用can),2. 表示推测，意为“可能”“或许”，用于疑问句或否定句,1. can 与could,4. 表示“许可”，可与may 换用。,You can go home now.,5. can 用于疑问句或否定句中时，表惊异、不相信等，意思是“可能、能够”。,Can this news be true? How can you be so foolish?,6. cant/ couldnt +have + done 表示对过去情况的否定推测,Susan cant have written a report like this.
4、,7. could + have + done 表示对过去能做而未做的事情感到惋惜，遗憾,Its a pity. Your class could have got the first prize.,can, could 和be able to的用法,She can/be able to sing the song in English. This machine can make you feel comfortable.,1.can, be able to都可表示“能力”,can的主语是人或物,be able to的主语是人,Well be able to finish the work
5、soon. I havent been able to see the film.,2.can只用于现在式和过去式(could)。 be able to可以用于各种时态。,could用于表示泛指过去的能力。如： I could read when I was four.,Although the soldier was badly wounded, he was able to tell what had happened. She ran fast but she couldnt /wasnt able to catch the bus.,3.表示特定的某一过去能力或表示成功地做了某事时，只
6、能用was/were able to， 不能用could。,He was able to flee Europe before the war broke out. He was able to swim halfway before he got tired.,表示过去的能力,注意can的惯用语 1.cannot (help/choose) but do 2.can but do 3.cannot help doing 4.cant help sb. doing sth. 5.cant help sb. do sth. 6.cant help (it) 7.cannot too,不得不，只能
7、 只好，不得不 忍不住 不能让某人不做某事 不能帮忙做某事 控制不住，没有办法 越越好,2. may 与might,1. 表示“许可”或“请求”，有“可以”的意思，口语中常用 might 代 may ,表示委婉语气。否定回答时用“must not”表“禁止，阻止”，不用 “may not”. “may not” 表示“可能不” 。,Eg: 1)- May I watch TV after supper?- Yes, you may. / No, you mustnt.2) Today is Sunday. She may not in her office now. can也可表示许可或请求，
8、但语气较强烈。,2. 表示可能性。 意为“或许，可能” might 比 may 可能性小。,Eg: 1) It might be true.2) They may be in the library now.,3. may/ might as well + 动词原形 “还是的好”,Eg: You may as well go and have a look.,4. May you +动词原形 表“希望、祝愿、祈求” “祝你”,Eg: May you succeed.,3. will 与would,1. 表“请求、建议”等。常用在疑问句中, 第二人称。用 would 比用will 委婉，客气些,
9、Eg: 1)Will you lend me your book?2) Would you like a cup of tea?,2. 用于表示意志或意愿。will 指现在，而would 指过去。,Eg: 1) Ill never do that again.2) They said that they would help us.,用于否定句中，表示“不肯、不乐意”,Eg: No matter what I said, he wont listen to me.,3.表示习惯性动作。 译作 “总是、惯于” will 指现在，would 指过去。,Eg: 1) Fish will die wi
10、thout water.2) Every evening, she would sit by window, deep in thought.,4. 表示功能，译作“能、行”,Eg: 1) That will be all right.2) This door wont open.,4. should,1. 用于表劝告、建议。 意为”应该、应当”。=ought to,Eg: You should keep your promise.,2. 用于表达合理的推断（ 意为 “应该”），或明显的结果（意为“可能”）。所涉及的事情几乎是事实。,Eg: 1) Its 7 oclock, he should
11、 be at home.2) They should have arrived by now.,3.表示惊讶，忧虑，惋惜等情绪，意为“竟会，竟然”,Eg: I find it quite astonishing that he should be so rude to you.,5. shall 与will,1. shall 与第一、三人称连用，且用在疑问句中时，表说话人征求听话者的允诺。will 与第二人称连用，且出现在疑问句中时，表示请求。 would 更客气。,Eg: 1) Shall we begin our discussion?2) Shall the driver wait?3)
12、 Will you speak louder, please?,2. shall的主语是第二、三人称的陈述句，表示说话人的允诺、警告、命令等语气。,Eg: 1)You shall get the book tomorrow.2) He shall be punished.3) You shall go with me.4) If you come to my house,I will show you my new painting.用在法律，条约，规章，预言等文件中，无论主语人称如何，一律用shall, 表示义务，规定。,允诺,警告,命令,6. must,1. 表示义务或强烈的劝告，意为“必
13、须”“应该”，其否定式表示“不应该”“不许可” “不准”“禁止”。,Eg: 1) You must finish your homework first.2) Children mustnt speak like that to their parents.,2. 回答 must 所在的一般疑问句时，否定回答用“neednt” “dont have to”.,Eg: -Must we finish the work tomorrow?-No, you neednt/ dont have to./Yes, you must.,3. 表推测，用于肯定句，意为“一定”“必然会”。,Eg: 1) Be
14、tty must be in the next room.2) He must be watering the flowers in his garden.,Must you go swimming in such a cold day?,4. must表示“偏要，硬要”，指做令人不快的事情,dare 和 need,惯用语 How dare you/he? 表达“愤怒，谴责”之意 I dare say. 我以为，我想 He is not here yet, but I dare say he will come later.,小结： 表能力 表允许 表推测表否定推测,can / be able
15、 to can / may might/may/could/can/should/ought to/ would/will/must cant / may not,情态动词 + have done这是历年高考热点之一， 可表示“推测、责备、怀疑”等多种意义。,一、表示对过去事情的推测或估计,1. must have done “想必或肯定已经做了某事”eg: The ground is rather wet, so it must have rained last night. 2. may/might have done “可能/大概已经做了某事”eg: Tom may have gone
16、to shanghai, but I still not sure about it. 3. cant/couldnt have done “不可能已经做了某事”eg: The ground is very dry, so it cant have rained last night 注：在疑问句中 can/could 表示对过去情况的疑问性推测，“可能已经了吗？”eg: Someone must have broken into our bedroom,Who could have done it?,二、表示对过去所发生事情的遗憾或责备,1. should/ought to have don
17、e “过去本该做而没做”eg: I really regretted wasting the hours when I should have studied hard, but it was too late.2. shouldnt/oughtnt to have done “过去不该做的事却做了”eg: Im very sorry for the words I shouldnt have said to you at that moment.3. could/might have done “本来能够做的事却没做”eg: He could have worked out the prob
18、lem.,He neednt have come. He didnt need to come.,他本没有必要来（实际也没来）,他本没有必要来（实际却来了）,4. neednt have done “原本不必做的事却做了”eg: Your home is not far from your school, so youneednt have left in such a hurry.,5. didnt need to do/ didnt have to do“ 没有必要做，实际也没做”eg: I didnt need to clean the windows. My sister did it
19、.,6. would rather have done “本想做却未做成” eg: I would rather have come to help you with yourEnglish, but I was too busy at that time.,1.-There were already five people in the car but they managed to take me as well.-It _a comfortable journey. A. cant be B. mustnt have been C. shouldnt be D. couldnt have
20、 been,D,2.The fire spread through the hotel very quickly but everyone _ get out. A. had to B. would C. could D. was able to,D,4. Peter _ come with us tonight, but he isnt very sure. must B. can C. may D. will,C,5. - Could I call you by your first name? - Yes, you_. A. will B. could C. may D. might,C
21、,6. Sorry, I m late. I _ have turned off the alarm clock and gone back to sleep again. might B. should C. can D. will,A,7.-Excuse me, but I want to use your computer to type a report. -You _ have my computer if you dont take care of it. A. shant B. might not C. neednt D. shouldnt,A,8. -When can I co
22、me for the photos ? I need them tomorrow afternoon.-They _be ready by 12 : 00 . A. can B. should C. might D. need,B,9. With so much work on hand, you _to see the game last night. A. mustnt go B. could have gone C. shouldnt go D. shouldnt have gone,D,10.Johnny, you _play with the knife, you _hurt yourself. A. wont ; cant B. mustnt ; may C. shouldnt ; must D. cant ; wouldnt,B,11.There is no light in the dormitory. They must have gone to the lecture, _? A. didnt they B. dont they C. mustnt they D. havent they,D,12. I missed the bus, so I _ go home on foot.A. must B. may C. can D. had to,D,
