情态动词
常见的情态动词有：
can 能
may 可以
will，would （表意愿）
need 需要
dare 敢
must 必须
have to 不得不
shall，should 应该（表义务）
ought to 应该
1.can，could 的用法
1.1表能力，有“能”、“会”、“能够”的意思
例如：Can you drive a car? 你会开车吗？
-----Yes, I can. 我会。
-
----No, I can't. 我不会。
1.2表允许，在口语中代替 may，有“可以”的意思
例如：Can I u your bike? 我可以用你的自行车吗？
1.3表示可能性，常用于否定句和疑问句
例如：Can it be true? 那会是真的吗？
Today is Sunday. He can't be at school. 今天是星期天。他不可能在学校里。
1.4过去式could表示的语气更加委婉、客气
例如：Could I come to e you tomorrow? 明天我可以来见你吗？
1.5 can 和 be able to 的比较
1) can 只有一般现在时和一般过去时两种时态(could)，其他时态要用be able to的形式
例如：I haven't been able to get in touch with her. 我一直没能和她联系上。
2) 通常can 和 be able to 可以互换
例如：He will come if he can.如果可能的话，他一定会来。
2.may，might的用法
2.1表示许可或征求对方的许可，有“可以”的意思。
例如：You may go now. 你可以走了。
May I u your computer? 我用一下你的电脑可以吗？
2.2回答以may开头的疑问句有如下表达法：
例如：May I smoke here? 我可以在这儿抽烟吗？
-----Yes, you may.
-----Yes, plea.
------No, you can't.
------No, you mustn't.
------No, you'd better not.
2.3表示猜测，通常只用于陈述句
例如：You may be right. 你可能是对的。
2.4过去式might表示的语气更加委婉、客气
例如：Might I u your pen for a while? 我能用用你的钢笔吗？
2.5在口语中can可以代替may表示许可，但can较随便，may更正式
例如：Can I u your bike, John? 约翰，我可以用一下你的自行车吗？
May I have a look at your licen plea, sir? 先生，我可以看一下你的执照吗
3.must 的用法
3.1表义务，“必须”
例如：You must talk to them about their study. 你必须同他们谈谈关于他们学习的事。
3.2在否定结构中表不许、禁止
例如：You mustn't leave here. 你不能离开这儿。
3.3表坚定的建议
例如：You must come and e us as soon as you get to Shanghai. 一到上海你就得马上来见我们。
3.4表推测，暗含有很大的可能性
例如：He must be ill. He looks so pale. 他肯定是病了。他的脸色那么苍白。
［注意］
may 暗含的可能性较小，must 暗含的可能性较大。
3.5关于must的简短回答：
例如：Must I clean the dining room at once? 我必须马上打扫餐厅吗？
------Yes, you must.
-日记300字大全
-----No, you needn't.
------No, you don't have to.
4.have to的用法
have to 虽属于情态动词，但它有人称、数的变化，它的疑问句否定句的构成也和其他情态动词有所不同。
4.1 have to表客观的需要和义务，must表主观认识
例如：I misd the train, so I had to take a taxi. 我没搭上火车，所以我只得打的。
4.2在疑问句和否定句中，have to多用助动词do构成，must则直接提前或加not。
例如：Did he have to do it? 他得做那件事吗？
―――He didn't have to do it. 他不需要做那件事。
4.3在否定句中，have to表示不需要，must表不允许。
例如：You don't have to go there. 你不需要去那儿。
You mustn't go there? 你不可去那儿。
4.4虽然must可以用在过去时态中，但是have to更能直接了当的表达过去时间概念。
例如：She must e Hubert that very night. 她必须在那个晚上见到休伯特。
I had to leave at six yesterday. 我得在昨天6点离开。
5.need 的用法
need既可用作情态动词，又可用作实义动词。作情态动词时，没有数和人称的变化，后接动词原形；作实义动词时，有数的变化和人称的变化，后接带to的不定式。
5.1用于否定句，表“不必”
例如：You needn't worry. 你不必担心。
I don't think you need worry. 我想你不必担心。
5.2用于疑问句，表“需要吗”
例如：Need you go? 你得去吗？
-----No, I needn't. 不必。
-----Yes, I must. 是的，我必须去。
5.3 need用作实义动词时，要注意始终以实义动词的标准贯彻到底
例如：（正确）Do you need to go there?
（错误）Do you need go there?
6.will和would的用法
6.1 will，用于构成将来时是助动词。用于表示“意志”“决心”“请求”是情态动词。would亦同理。
例如：He'll be here this afternoon. 今天下午他会来这儿。（助动词）
Will you tell her that I'm here? 请您告诉她说我在这儿，好吗？（情态动词）
6.2用于各种人称，表示“意志”“决心”“允诺”
例如：I will try. 我愿一试。
6.3在疑问句中用于第二人称，提出请求或询问
例如：If you want help， let me know, will you? 如果你需要帮助，让我知道，好吗？
Will you type this, plea? 请打印这个，好吗？
Won't you sit down? 请坐下，好吗？
6.4 would比will客气委婉
例如：Would you help us, plea? 请您帮助我们，好吗？（表请求）
I'd go there with you. 我要和你一块到那儿去。（表意愿）
Dad wouldn't allow it. 爸爸不会允许这件事。（表许可）
7.shall和should的用法
7.1 shall用于构成将来时是助动词，shall用于征求对方的意见，表示“决心”是情态动词
例如：Perhaps I shall pay a visit to England this winter. 可能今年冬天我会去英国观光。（构成一般将来时，助动词）
Shall I turn on the light, Mom? 妈妈，我把灯打开好吗？（用于征求对方的意见，情态动词）
I shall be there. 我会到那儿去的。（表“决心”，情态动词）
7.2 should用于构成将来时是助动词。should用于表示“应当”“猜测”是情态动词
例如：We thought we should never e you again. 我们以为再也见不到你了。（构成一般过去将来时，助动词）
I should write some letters tonight.今晚我得写几封信。（表“应当”，情态动词）
They should be there by now.他们现在可能到了。（表“猜测”，情态动词）
8.ought to的用法
ought to 表示应该、理应做什么
例如：You ought to clean the classroom , for it is your turn today.你应该把教室打扫了，
因为今天是你值日。
9.情态动词表示“推测”的用法
情态动词表示“推测”时，要记住以下两种推测和形式
推测：
①对过去发生动作或状态的推测；
②对现在状态的推测。
两种形式：
①用情态动词加完成时态表示对过去发生动作或状态的推测；
②用情态动词加动词原型表示对现在发生动作或状态的推测。
具体用法如下：
9.1 must have done表示过去一定做了什么，语气十分肯定
例如：You must have finished your work.你一定完成了你的工作。
9.2 can’t have done表示过去不可能做了什么，语气也比较肯定(是上面的否定形式)
例如：He can’t have gone to Beijing, for I had a talk with him just now.他不可能去过北京，
因为我刚和他交谈过。
9.3 needn’t have done表示过去没有必要做什么但已经做了。
例如：You needn’t have come earlier. 你不需要来这么早的。
9.4 should have done过去该做什么但没有做。(含有责备的意思)。
例如：You should have started earlier.你本应该早点开始的。
9.5 shouldn’t have done表示过去不该做什么但做了。(含有责备的意思)
例如：You shouldn’t have helped him, he could do it himlf.你本不该帮助他的，他能自己做。
9.6 ought to have done表示过去该做什么而没有做。(是职责和义务)
例如：You ought to have helped him. (but you didn’t.)春条怎么贴你应该帮助他的。
9.7 can/could do sth.表示对现在情况的猜测，常用于否定句、疑问句或感叹句中。
例如：This news can’t be true.草鱼怎么做最好吃 这消息不可能是真的。
9.8 may/might do sth. 表示对现在情况的猜测，常用于肯定句中。
例如：Mr.Wang may know Professor Li’s telephone number.王先生也许知道李教授的电话号码。
针对性练习：
1) You____ all tho clothes! We have a washing machine to do that sort of thing
A) needn't have washed B) shouldn't have washed
吸氧有什么好处 C) must not have washed D) can not have washed
2) John's score on the test is the highest in the class; he____ last night.
A) should study B) should have studied C) must have studied 什么星座D) must have to study
3) The room is in a terrible mess; it ____cleaned. (CET-4, 1996,6)
A) can't have been B) shouldn't have been C) mustn't have been D) wouldn't have been
4) Nobody knows how people first came to the islands. They ____ from South America on rafts.
A) must have sailed B) can sail C) might have sailed D) should have sailed
5) Mary was not in her bedroom yesterday afternoon. She ____ in her classroom.
A) should have been B) must have been C) must be D) should be
6) Bob said he was going to join our club but he didn't. He ____ his mind.
A) can't have changed B) wouldn't have changed
C) must have changed D) shouldn't have changed
7) You____ to town to e the film yesterday. It will be on TV tonight.
A) needn't go B) had better not go C) should not go D) needn't have gone
8) We____ the letter yesterday, but it didn't arrive.
A) must receive B) ought to receive C) must have received D) ought to have received
9) With all the work on hand, he____ to the cinema last night.
A) mustn't go B) shouldn't have gone C) could not go D) couldn't have gone
10) Eve was late for class again. She ____earlier.
A) should get up B) must get up C) need to get up D) should have got up
11) I am feeling sick. I____ so much chocolate.
A) needn't have eaten B) couldn't have eaten
C) mustn't have eaten D) shouldn't have eaten
12) I didn't nd out my application form last week, but I ____.
但丁是哪国人
A) had B) would do C) should have D) might have to
13) Walking alone in the derted village, John was scared. He thought he____ Tom to go with him.
A) might have asked B) should asked C) must have asked D) should have asked
14) When I got to the cinema, the film had already started; I____ there earlier.
A) ought to get B) ought to have got C) must have got D) must get
15) The road was muddy. It____ last night.
A) must rained B) must have rained C) must be rained D) could have rained
16) She can speak quite fluent English. She____.
A) must been in the U.S.A. for some time
B) must have been in the U.S.A. for some time
C) should have been in the U.S.A. for some time
D) May be in the U.S.A. for some time
17) You should bear in mind that he is not so strong as he____.
A) was ud to be B) ud to be C) was ud to D) u to
18)---- “We didn't e him at the exhibition yesterday.” ---- “He ___it.”
A) mustn't visit B) can't have visited C) should have gone to e D) may e
19) Mary ____my letter, otherwi she would have replied before now.
A) should have received B) has received
C) Couldn't have received D) ought to have received
20) I ____ you a valuable prent for your birthday, but I was short of money.
湖州博物馆 A) would have liked to give B) liked to give
C) have liked to give D) would like to give
21)--- “Where ____ my umbrella?” --- “Somebody ____ it away by mistake.”
A) is, must have taken B) is, must take C) have been, must take D) is, takes
22) What ____ would happen if the director knew you felt that way?
A) will you suppo B) you suppo C) do you suppo D) you would suppo
23) Two eyes ____e more than one.
A) can B) may C) will D) should
24) ____ you continue in your efforts and achieve new and greater success.
防晒霜怎么用才正确 A) Would B) Will C) May D) Should
25) We ought to help each other in our work, ____?
A) oughtn't we B) should we C) shouldn't we D) ought to we
26) Tom ____ better than to ask Dick for help.
A) shall know B) shouldn't know C) has known D) should have known
27) You ____ your tooth pulled out before it rot completely.
A) had better got B) had to get better C) had better to get D) had better get
28) When we got to the cinema, the film hasn't started yet, so we ____.
A) needn't hurry B) didn't need hurry C) needn't to hurry D) needn't have hurried
29) It was really very dangerous; you ____ him riously.
A) might have injured B) could injure C) should have injured D) must injure
30) As he had heart attack, he was told that he ____ continue the work.
A) needn't B) may not C) mustn't D) can't
31) An Englishman who ____not speak Italian was once traveling in Italy.
A) must B) could C) may D) might
32) I ____like to make a suggestion.
A) could B) would C) must D) might
33) I know things are hard with you, but you ____try to get over the difficulties.
A) can B) may C) must D) ought
34 I can't find the recorder in the room. It ____ by somebody.
A) may have been taken away B) may leave C) may take away D) must have taken away
35) He ____the 9:20 train becau he didn't leave home till 9:25.
A) can reach B) could catch C) may not catch D) couldn't have caught
