五年级英语上册教案-二手房买卖合同样本

情态动词
定义:
情态动词是一种 本身有一定的词义,但要与动词原形一起使用，给谓语动词增添情态色彩，表示说话
人对有关行为或事物 的态度和看法，认为其可能、应该或必要等。
情态动词后面加动词原形。
分类：
情态动词有四类：
①只做情态动词：must,can(could),may(might),ought to
②可做情态动词又可做实义动词：need,dare
③可做情态动词又可做助动词：shall(should),will(would)
④具有情态动词特征：have(had) to,used to
位置:
情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词
则在主语之前。
I can see you. Come here.
我能看见你，过来吧。
He must have been away.
他一定走了。
What can I do for you?
我能帮你吗？
How dare you treat us like that！
你怎能那样对待我们！
特点:
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加
。 个别情态动词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。情态动词没有非谓语形式，即没
有不定式，分词，等形式。
He could be here soon.
他很快就来。
We can't carry the heavy box.
我们搬不动那箱子。
I'm sorry I can't help you.
对不起，我帮不上你。
基本助动词与情态助动词最主要的区别之一是，基本助动词本身没有词义 ，而情态助动词则有自己
的词义，能表示说话人对有关动作或状态的看法，或表示主观设想：
What have you been doing since? （构成完成进行体，本身无词义）
I am afraid I must be going. （一定要）
You may have read some account of the matter. （或许已经）
除此之外，情态助动词还有如下词法和句法特征：

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1） 除ought和used以外，其他情态动词后面只能接不带to的不定式。如果我们把ought to和u
sed to看做是固定词组的话，那么，所有情态动词无一例外地只能接不带to的不定式：
We used to grow beautiful roses.
I asked if he would come and repair my television set.
2） 情态助动词在限定动词词组总是位居第一：
They need not have been punished so severely.
3） 情态助动词用于第三人称单数现在时的时候，没有词形变化，即其词尾无-s形式：
She dare not say what she thinks.
4） 情态动词没有非限定形式，即没有不定式和分词形式，也没有相应的动名词：
Still, she needn't have run away.
5） 情态助动词的“时”的形式并 不是时间区别的主要标志。在不少场合，情态助动词的现在时和过
去时形式都可以表示现在、过去或将来 时间：
Would you mind very much if I ask you to do something?
She told him he ought not to have done it.
6） 情态助动词之间是相互排斥的，即在一个限定动词词 组中只能出现一个情态助动词，但有时却
可以与have和be基本助动词连用：
You should have washed the wound.
Well, you shouldn't be reading a novel.
用法
首先它是动词 ，而且不同于行为动词，行为动词表示的是可以通过行为来表达的动作（如写，读，
跑），而情态动词只 是表达的一种想法（如能，也许，敢）。
用法是：情态动词+行为动词原形
例句：I can read this sentence in English.
我能用英语读这句话。
情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语, 只能
和其他动词原形构成谓语。
We can be there on time tomorrow.我们明天能按时去那儿。
May I have your name? 我能知道你的名字吗？
Shall we begin now?我们现在就开始吗？
You must obey the school rules.你必须遵守校规。
情态动词数量不多,但用途广泛,主要有下列:
can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would),h
ave (to) ,had better.
功能
助动词(auxiliary)主要有两类：基本助动词(primary auxiliary)和情态助动词(modal auxiliary)。基本
助动词有三个：do, have和be；情态助动词有十三个：may, might; can, could; will, would; shall,
should; must, need, dare, used to, ought to. 上述两类助动词的共同特征是，在协助主动词构成限
定动词词组时，具有作用词的功能：

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1） 构成否定式：
He didn't go and neither did she.
The meeting might not start until 5 o'clock.
2） 构成疑问式或附加疑问式：
Must you leave right now?
You have been learning French for 5 years, haven't you?
3） 构成修辞倒装：
Nowhere can he obtain any information about his sister.
Hardly had he arrived when she started complaining.
4） 代替限定动词词组：
A: Who can solve this crossword puzzle?
B: Tom can.
A: Shall I write to him?
B: Yes, do.
情态动词的用法要点

一． can和could
情态动词









cancould
用法

表示能力（体力、知识、技
能）
(表示过去有能力用could)

例句
1．“I don’t think Mike can type.”
2．I can speak fluent English now , but I couldn’t last year.
3．Can you lift this heavy box?（体力）
4．Mary can speak three languages.（知识）
5．Can you skate?（技能）
eyes can see more than one. 两只眼比一只眼看得清。
the girl read before she went to school? 这女孩上学前能识字
吗？
在肯定句中，表示客观可能
1． As a human being, anyone can make a mistake.
性，（客观原因形成的能力）。
2． I’m confident that a solution can be found.
并不涉及具体某事会发生，
3． He can be very forgetful sometimes.
常用来说明人或事物的特4． I may stay at home this weekend.（实际可能性）
征。要表达具体某事实际发5． Peter might come to join us.(实际可能性)
生的可能性时，不用can，需6． It will be sunny in the daytime ,but it could rain tonight.(实际可能性)
用could，may，might。
7． ’ve changed the timetable, so we can go by bus instead.
8． hall can hold 500 people at least.
9． The temperature can fall to –60℃, that is 60℃ below freezing.
气温可降至—60℃，也就是零下60℃。
10． 11..He can´t (couldn´t) have enough money for a new car. 他不
可能有足够的钱买新车。
11． 12 You mustn´t smoke while you´re walking around in the wood.
You could start a fire. （实际可能性）
12． 在林子里走时勿吸烟，那样可能会引起火灾。


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表示请求和允许。表示请求，
口语中常用could代替can，
使语气更委婉。
用can和 may来回答，不能
用could或might。
we turn the air conditioner on?
police officer can insist on seeing a driver’s license.
soccer, you can’t touch the ball with your hands.
you have her call me back when she gets home, please?
5.I wonder if I could just ask you to sign this.
6. Could I borrow your dictionary?
---Yes, of course, you can.
No, I'm afraid notNo,you cann’tNo,you may not.

1． It can’t be easy caring for a man and a child who are not your own.
2． Can the man over there be our head master?
Tom didn't leave here until five o'clock, he can't be home yet. 如果汤
姆五点才离开这儿，他此时一定还未到家。
1． Can this be an excuse for not giving them help?
2． This can’t be true.
3． How can you be so crazy.
4． this be true?
5． can you be so careless!
6． cannot be done by him.
7． Where can (could) they have gone to? 他们会去哪儿了呢？
8． He can´t (couldn´t) be over sixty. 他不可能超过六十岁。
9． How can you be so careless? 你怎么这么粗心？
表示对现在的动作或状态进
行主观的猜测，主要用在否
定句和疑问句中。
表示惊异、怀疑、不相信等
态度，主要用在否定句、疑
问句和感叹句中。

10． 特别说明：
（1） could用来表示请求时，语气委婉，主要用于疑问句，不能 用于肯定句，答语应用can（即：could不能用
于现在时态的简略答语中）。如：
——Could I use your dictionary?
——Yes, you can.(否定回答可用：No, I’m afraid not.)
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。
---- Could I come to see you tomorrow?
---- Yes, you can. ( No, I’m afraid not. )

(2) can和be able to辨析
can(could)和be able to都可以表示能力，意思上没有区别。但can只有现在式和过去式，而be able to则
有更多的形式。如：
I’ve always wanted to able to speak fluent English.
Those bags look really heavy, are you sure you’ll be able to carry them on your own?
但是，表示在过去某时的某一场合经过一番努力，终于做成了某事，通常不 用could，而用waswere able
to来表示。could：有潜能，但并未做到
这时，waswere able to相当于managed to do或succeed in doing。如：
After the accident it was a long time before she was able to walk again.
The fire was very big, but most people were able to escape from the building.
I can sing many English songs.我会唱许多英文歌曲。
We were able to return to our campsite before the heavy rain.我们在下大雨前设法会到了野营地。

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He was able to swim across the river and escaped being caught.他游到了河对岸，没有被抓住。
在否定句中，cancould与be able to几乎没有什么差别，两者可以互换。例如：
She wasn’t able tocouldn’t cook French dishes.她不会做法国菜。
(3) 惯用形式“cannot …too…”表示“无论怎么……也不（过分）”。如：
You cannot be too careful.你越小心越好。
惯用形式“cannot but+ 不定式（不带to）”表示“不得不，只好”。如：
I cannot but admire her determination.我不得不钦佩你的决心。
二．may和 might
情态动词









maymight
用法
表示允许、请求。否定回答一般用must
notmustn’t,表示“禁止、阻止”之意，但也可
以用had better not (最好别)或may not（不可
以），语气较为委婉。
在表示请求、允许时，might比may语气更委
婉些。而不是过去式，用May I征询对方许可
在文体上比较正式，在口气上比较客气，在日
常用语中，用Can I征询对方意见更为常见。
否定回答时可用can’t
或mustn’t，表示“不可以，禁止”。
或者
肯定回答可以用 yes,please. Certainly.
例句
1． May I come in and wait?
2． ——May I smoke here?
——No, you mustn’t(或No, you’d better not.)
I borrow your pen?
2.I wonder if I might speak to your son.
3． Might May I smoke in this room?
4． ---- No, you mustn’t.
5． 4. MayMight I take this book out of the room?
---- Yes, you can. (No, you can’t mustn’t. )
You may drive the car.
— Might I use your pen? — No, you mustn't.
表示可能性的推测，通常用在肯定句和否定句
1． It may rain this afternoon.
中，含有“或许”“大概”“可能”之意；用
2． She might come to join us this afternoon.
might代替may时，则语气显得更加不肯定。
3． I suppose he might have missed the train.
may might be very busy now.
5．Your mother may might not know the truth.
1． May you succeed.。
may用于祈使句表示祝愿
2． May you have many more days as happy as this
one.
3． May she rest in peace.愿她安息。
惯用句式：
“may well+ 动词原形”，意为“完全能，很可
能”，相当于to be very likely to

“may as well或might(just)as well+动词原形”
意为“最好，满可以，倒不如,不妨,”，相当于
“had better或there is no reason to do anything
else.
1． It may well change forever the way you look at
Greek art.
2． There may well be a real problem here.
3． There is nothing to do, so I may as well go to bed.
4． You may as well tell us now, we’ll find out sooner
or later.
5． I suppose we might as well go home.
6． And if you have to plough the field anyway, you
might as well plant it at the same time.
that is the case, we may as well try.
1. He told me that I might smoke in the room. 他
告诉我可以在房间里抽烟。

might 间接引语中指过去。表可以。

二．must和have to

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情态动词





must
用法 例句
表示“必须，应该，一定”之意，语气比should，
1． You must come to school on time.
ought to强烈。其否定形式mustn’t表示“不准，
2． Everybody must obey the law.
不应该，禁止”等意.
3． You mustn’t drive so fast in the street.
4． We mustn’t waste any more time.
5． I must finish my work today.
6． Must I return the book tomorrow?
7． play is not interesting. I really must go
now.

在回答带有must的问句时，否定回答常用needn’t
或don’t have to，表示“不必”，而不用mustn’t.
1．—Must I come back before ten?
—Yes，you must.(No, you needn’t)
we hand in our exercise books today?
— Yes, you must. (No, you don’t have to.)
表示有把握的推测，意为“一定、准是、想必”，
1． This must be your pen.
只用于肯定句中。
2． You must be hungry after a walk.
它的否定或疑问式用can代替must
3． There must be a hole in the wall.
4． You’re Tom’s good friend, so you must know
what he likes best.
5． mother must be waiting for you now.
6． He must be staying there.
7． 他现在肯定呆在那里。
试比较和第一种用法的区别
He must stay there.
他必须呆在那。

10． The film is not interesting. I really must go
now.
11． I have to go now, because my mother is in
hospital.
12． My brother was very ill, so I had to call
the doctor in the middle of the night. 我弟弟病
得很厉害，我只得半夜里把医生请来。(客观
上需要做这件事)
13． 4. Must I clean all the room?
14． 5. I must go over the test paper again to
see if there are any mistakes.我必须再检查一
遍试卷看看是否有错误。
15． 6. The teacher said that there were many
mistakes in my test paper, so I had to go over it
again.老师说我试卷中有很多错误，所以我只
好再检查一遍。
18． 7.．I had to work hard when I was your
age.
have to
也可拼做
have got
to。


8． “必须，不得不”，意义与must相近。但must
表示的是说话人的主观看法，而have to则往
往强调客观需要,有被动接受的意思。无疑问
句形式，疑问句用must 代替。
9．
16． must只有一种形式，即现在式与过去式
都是一种形式，在间接引语中must可用于表

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示过去时间.而have to则涉及各种人称、时
态等方面的变化形式。
17．
19． 8.．I will have to learn how to use a
computer.
20． 9．In order to take the exam, we’ll have to
finish the whole book by the end of this month .
21． 10. told her that she must give up
smoking. 我叫她必须戒烟。
22．
两者的否定意义不同，mustn’t表示“禁止，不许”，
1． You mustn’t go there.
don’t have to表示不必。
2． You don’t have to go there.
四．shall和should
情态动词
shall
用法
用于第一，三人称构成的疑问句，表示征求对
方意见或请求指示
例句
1． Shall I open the window?
2． Shall we say 6 o’clock, then?
3． What shall I get for dinner?
we begin our lesson?
4． shall he be able to leave the hospital?
5． Shall the boy wait outside? 让那男孩在外面等
吗？
用于第二、三人称陈述句中，表示说话人给对
方的命令、警告、决心、允诺或威胁。
1． Don’t worry, you shall get the answer this
afternoon.(允诺)
2． He shall be sorry for it one day, I tell you. （警
告）
3． You shall do as I say. (命令)
4． If you children don’t do as I tell you, you shall
not go to the party. (威胁)
5． 5. You shall fail if you don’t work hard.(警告)
6． 6. He shall have the book when I finish it.(允诺)
7． 7. He shall be punished.(威胁)
8． shall do as I say. 按我说的做。（命令）
9． shall have my answer tomorrow. 你明天
可以得到我的答复。（允诺）
10． shall be sorry for it one day, I tell
you. 有一天他会后悔的，我告诉你。（警告）
11． g shall stop us from carrying out
the plan. 什么也不能阻止我们执行这项计划。
（决心）
should 表示劝告或建议，意为“应该”其同义词是
ought to；在疑问句中，通常用should代
替ought to
12．
13．
14．
should I do?
I trust him?
should read his new book.
15． 4. You should go to class right away.
16． I open the window?
17． You should be polite to your teachers. 你
对老师应该有礼貌。
18． You shouldn´t waste any time. 你不应该

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浪费时间。
19．
表示推测，用在肯定句中，对现在的情况或可
20． It should be a nice day tomorrow.
能发生的事的主观推测或期待。意为“想必，
21． Try phoning Robert, he should be home
大概，或许” now.
22． He should be around sixty years old.
23． film should be very good as it is
starring first—class actors.
24． 这部新电影是一流演员主演的，估计拍
得很好。
25． should be home by now. 照说他
们现在应当已经到家了。
26． Ask Tom to ring me up if you should see
him. (你万一见到汤姆，请让他给我打个电话)
27． Should I be free tomorrow, I’ll come. (万
一我明天有时间，我就过来)
28． If things should change suddenly, please let
me know. (万一情况突变，请通知我)
4. Ask her to ring me up if you should see her.
你万一见到她，请让她给我打个电话。
5. If you should change
your mind, please let us know. 万一你改变
主意，请通知我们。
I (If I should) be free tomorrow I will
come. 万一我明天有时间，我就来。

用于疑问句或感叹句中，表示意外、惊异的情
绪，意 为“竟会”，与why，what，how，who
连用，如果是疑问句。则不需要回答。
1． Why should anyone want to marry Tony?
2． Don’t ask me. How should I know?
should you be so late today? 你
几天怎么来得这么晚？
4. — Where is Betty living? — 贝蒂住在
哪里？
— How should I know? — 我怎么会
知道呢？
5.I don't know why you should think that I did
it. 我真不知道你凭什么认为这件事是我干的。

表示说话人的一种谦逊、客气、委婉的语
气。

① I should think it would be better to tr
y it again. 我倒是认为最好再试一试。
② You are mistaken, I should say.
依我看，你是搞错了。
③ I should advise you not to do that.
我倒是劝你别这样做。

8
还可以用 在if引导的条件句中，表示一件事听
起来可能性很小，但也不是完全不可能，相当
于“万一” 的意思。从句谓语用should+动词
原形构成，主句都一定用虚拟语气

五．will和would
情态动词
willwould
用法
用于表示意志，愿望或意愿。will
指现在，would指过去。
例句
1． He is the man who will go his own way. (他是个自行其
是的人。)
2． They said they would meet us at 10:30 at the station.
3. I will never do that again.
4. They asked him if he would go abroad.
said he would help me.
6.I’ll do my best to catch up with them.
7.I will do anything for you. 我愿为你做任何事。
is so blind as those who won´t see. 不愿看的人眼最
瞎。
you will read the book, I´ll lend it to you. 如果你愿意
读这本书，我会把它借给你。
They would not let him in because he was poorly dressed.
他们不让他进去因为他衣着破旧。
I said I would do anything for you. 我说过我愿意为你做任
何事。

表示请求、建议等，will接近命
1． Will you please take a message for him?
令的口气。用would比用will委
2． Would you please tell me your telephone number?
婉、客气。Would like to do = want
Would you pass me the ball, please?
4 Would you like to go with me?
to 想要，为固定搭配
否定句用will，一般不用would,
5. Would you like some cake?
6 Won't you sit down?
won't you是一种委婉语气。
表示习惯或倾向，意为“总是，
惯于”。Will指现在，woul d指过
去。would表示过去习惯时比
used to正式，且没有“现已无此
习惯”的含义。
used to可表示过去的习惯动作
和经常的情况，而would只表示
过去的习惯动作,不表示状态和
情况。

1． Fish will die without water.
2． People will talk. (人们总会说闲话。)
3． When we worked in the same office, we would often
have coffee together.
4． During the vacation, he would visit me every other day.
5． The boy will sit there hour after hour looking at the
traffic go by.
那男孩常常坐在那里好几个钟点，看着车辆行人通过。
used to ∕would smoke while writing. 过去他写东西时
常抽烟。
used to be fat. 她过去很胖
表示推测，意为“很可能，大概”。
1． These things will happen.
will表示推测比should把握大，
2． That will be the messenger ringing.
比must把握小。
3． It would be about ten o’clock when he left home.
4． It would be about ten o’clock when she left home.
表示功能，意为“能，行”。惯
1． That will be all right.
用形式：will dowould do表示
2． Either pen will do.
“解决问题”、“就行”。 3． It would not do to work too late.（工作太晚不行。）
用于否定句中，意为“不肯”、“不
乐意”

1.I won’t listen to your nonsense.
matter what I said, he wouldn’t listen to me.
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Will 用于叙述真理时
用于表示具有某种功能时
will float on water.油能浮在水面上。
will die.人总会死的。
door will not open.门打不开。
2 The car will not start.车子启动不了。
特别说明：would与used to辨析
would可用来表示过去反复出现的动作，但不能表示过去存在的状态，所以我们不能说：“she would be a quiet girl.”
另外，would强调过去某种特定情况下的活动，是完全过去的事情，同现在没有联系。而used to则着眼于过去
和现在的对比，隐含现在已不存在，动作或状态都可表示。Would可以表示不规则 的习惯，used to则不可。如：
He used to be a naughty boy and cause trouble.
I used to get up at six in the morning.
Sometimes she would take a walk in the neighboring woods.
In those days, whenever I had difficulties, I would go to Mr. Chen for help.
六．need和dare
情态动词







need
用法
用于表示“需要，必要”之意。做情态动词
时，仅用于否定句和疑问句，（在肯定句中一
般用m ust, have to, ought to, should代替。
）只有现在时，
例句
1．—Need we leave soon?
—Yes, you must.(No, you needn't)
You needn’t come so early.
2. ---- Need I finish the work today?
---- Yes, you must. No, you needn’t.
3. --Need I come? --Yes, you must. --我需要来吗？ --
需要。
4You needn´t telephone him now. 你现在不必打电话
给他。
5.I don´t think you need worry. 我想你不必发愁。
dare not go out alone at night. 她晚上不敢一个
人出去。
dare you say I´m unfair? 你竟敢说我不公平？
Not one of them dared mention this. 他们谁也不敢提
这件事
做实义动词时，其变化与一般的实义动词相
1. A job like nursing needs patience and
understanding.(need+名词，need
同，有人称、时态和数的变化，后接带to的
understanding=need to be understood,需要被理解)
不定式或者名词。,过去式用needed、did you
2．He needs to see a doctor.(need to do)
need?和didn't need,肯定式用
3．Do you still need volunteers to help clean up after the
needsnee dedneed,疑问式用do、does、did提
party?(need somebody to do something)
问，否定式要在前面加don't、doesn't、didn't
4．They didn't need to start so early.(do not need to do)
（need doing = need to be done ）表被动
don´t need to do it yourself. 你不必亲自做这件
事。
need to tell them the news. 我们需要把这消息告
诉他们。
table needs painting (to be painted.). 桌子需要油
漆一下。
should dare to give our own opinion. 我们要敢于
提出自己的观点。
did not dare (to) look up. 他不敢抬头看。
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10..I dare day he´ll come again. 我想他会再来的。

dare
用于表示“敢于”之意。做情态动词，没有
人称和数的变化，主要用于否定句、疑问句
和条件状语从句中。过去式形式为dared。

1．—Dare you tell her the truth?
—Yes, I dare. No, I daren’t.
3． How dare you accuse me of lying!
4． He daren’t admit this.
5． How dare you say I’m unfair?
6． He daren’t speak English before such a crowd, dare
he?
7． If we dared not go there that day， we couldn’t get
the beautiful flowers.

用作实义动词时，其变化与一般的实义动词
1． Only a few journalists dared to cover the story.
相同。在肯定句中，dare后接带to的不定式；
2． He doesn’t dare (to) go there alone.
否定句中，dare后既可接带to的不定式，也
3． Don’t you dare (to) touch it?
可接不带to的不定式。
to swim across this river.
5. He doesn’t dare (to) answer.
6. He needs to finish his homework today.
7．I dare to swim across this river.
does not dare (to) answer.
9 .Don't you dare (to) touch it!
10.I wondered he dare (to) say that.
11. He needs to finish it this evening.


七．ought的用法：
情态动词


ought
do
用法
表示“应该”之意
to
表示推测。注意与must表示推测是的区别
例句
1． You ought to take care of him.
2． —Ought I go now?
—Yes, you ought to. No, you oughtn’t to.
3You ought to bring the child here.
1． He must be home by now. (断定他已到家)
2． He ought to be home by now. (不十分肯定)
3． This is where the oil must be. (比较直率)
4． This is where the oil ought to be. (比较含蓄)
had better do sth
had better not do sth
It is pretty cold. You'd better put on my coat.
She'd better not play with the dog.
If I have a choice, I had sooner not continue my studies
at this school.
I would rather stay here than go home. = I would stay
here rather than go home.

had bette
表示最好

would
rather

would
rather do


表示宁愿,宁可
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would
rather not
do

would
rather…
than… 宁
愿……而
不愿。

would
sooner,

had rather
had sooner
说明：should与ought to 表示“应该”时的区别
should 表示自己的主观看法，
ought to的语 气中，含有“按道理应该……”之意。(客观推测)，若要反映客观情况或涉及法律义务和规定，
一般用 ought to。ought to表示义务或责任，比should语气重。
must(主观推测)。如：
should help them with their work.
are his father. You ought to get him to receive good education.
must be home by now.
ought toshould be home by now.
is where the oil must be.
is where the oil ought toshould be.
7.I should help her because she is in trouble.
ought to take care of the baby.
2) 表示劝告、建议和命令。should, ought to可通用，但在疑问句中常用should。
1. You should ought to go to class right away.
2. Should I open the window?
八．“情态动词+have done”用法
情态动词+have done
must have done
用法
表示主观上对过去已经发生的行 为进
行推测，意为“想必，准是，一定做了
某事”肯定句中。否定句用can 代替
must
例句
1． She must have gone through a lot.
2． He must have visited the White House
during his stay in the United States.
maymight have done
has gone to work, but her bicycle is
still here.
---She must have gone by bus.
表示对过去已发生行为的推测，意为
1． You may have learnt the news.
“也许或许已经（没有）……“。一般
2． He may not have heard his name called.
用于肯定句或否定句中，不用于疑问
3． Sorry I’m late. I might have turned off
句。用might则表示语气更加不肯定。 the alarm clock and gone back to sleep
again.

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can…have done
cannot have done
表示对过去发生的行为的怀疑和不肯
定，通常用在否定句和疑问句中。（can
换成could 时语气委婉）
否定句表示：过去一定不。。。
1． Where can she have gone?
2． Could he have done such a foolish
thing?
3． The boy can’t have finished reading the
book so soon because it is difficult even
to an adult.
1． He could have killed himself driving
at a dangerous speed.
2． You could
considerate.
have been more
could have done 可用于肯定句中，表示“可能已经……”
之意，几乎等于maymight have done。后者更委婉一些。此外，还可以表示过
去能做而没做的事，有一种对过去为付
诸实施的事情 的惋惜。
或”过去可能。。。
或本来能。。。而实际没有


3． You could have done better, but you
were too careless.
4． She could have been his wife.
她以前可能是他的妻子。
她本应该是他的妻子。
1． You should not swim in that sea. You
might have been eaten by a shark.
2． He might have given him more help,
thought he was busy.
1． He should have known that the police
would never allow this sort of thing.
2． You shouldn’t have done it so
carelessly.
3． You ought to have returned the book
earlier.
4． You ought not to have refused his offer.
5． should have finished it.
6． 6.I should have helped her, but I ne
ver could.
7． 7. You should have started earlier.
8． You ought not to have taken the book
out of the reading-room.
might have done 表 示“本来可能……，但实际上没有发
生的事情”。另外，还可以表示“本来
应该或可以做某事” 之意，含有轻微的
责备语气。
用于肯定句时，表示本该做某事，而实
际上未做；用于 否定句时，则表示不该
做的事反而做了。
shouldought to have done
needn’t have done 表示做了本来不必去做的事。注意：
didn’t need to do表示“没必要做而实际
上也没有做某事”
needn’t have watered the plants, for it
is going to rain.
2.I didn’t need to buy the dictionary. I had a
copy at home.
needn't have waited for me.
had better have done 用于事后的建议，含轻微责备的口吻， had better have started earlier.
意为“当时最好做了某事”，其否定式 had better not have scolded her.
had better not have done表示相反的含
义。
表示“当时宁愿做了某事”，其否定式
would rather not have done表示相反的
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would rather have done 1． 1．I would rather have taken his advice.
2． 2．I would rather not have told him the

含义，两者都表示“后悔”之意。
must to have been doing等

表示对过去某时正发生的事情的推测
情态动词后跟进行式，表示“ 想必正
在……”，“可能正在……”，“应当正在”
等意。

truth.
1--Why didn't you answer my phone call?
---Well, I must have been sleeping, so I
didn't hear it.
2. It´s twelve o´clock. They must be having
lunch. 现在是十二点。他们一定正在吃
饭。
may be discussing this problem. 他
们可能正在论讨这个问题。
can´t be telling the truth. 他说的不可
能是真话。
shouldn´t be working like that. She´s
still so weak. 她不应当那样干，她身体仍
那么虚。
情态动词表示猜测
肯定：must>should>could>may>might
否定：can’t>shouldn’t>couldn’t>may not>
表示要求，命令时，语气由 should（应该）、had better最好）、must（必须）渐强。
必须掌握情态动词表示推测语气时的反意疑问句。例如：
The road is wet. It must have rained, hasn’t it?
The road is wet. It must have rained last night, didn’t it? (多了过去时的时间状语)
I met him on his way home. He can’t be in the library now, isn’t he? The coat is too close to the fire. It might get burnt,
doesn’t it?


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