情态动词
1. 常用的情态动词有
can could
may might
must have to
文武两全shall
should ought to
will would
need dare
情态动词无人称变化，后面接不带to的动词不定式，即跟动词原形。
2. must 的用法如下：
1) must 表示“必须，必要”
a. 在肯定陈述句中。
You must rely on yourlf.
You must pay the money.
b. must 意为“必须，必要”，其否定式为needn’t 或don’t have to 不必
< You need not be back by 10 o’clock.
You don’t have to be back by 10 o’clock.
You mustn’t be back by 10 o’clock.( wrong)
c. 在疑问句中。
---Must I be back here before supper?
---Yes, you must.
新生儿怎么拍奶嗝
(No , you needn’t / don’t have to.)
* mustn’t是表示“禁止”。
You mustn’t talk loudly here.
You mustn’t spit here.
2) must 表猜测，只用于肯定句，可译成：准是，肯定是。（其否定、疑问句用can.）
(表示根据逻辑推理必然要发生某事.)
a. 用“主语+must + 动词原形”表示对现在发生的事情的推测，常翻译为 “准是…”
eg. The teacher must be in the office, for the light is on.
That fat man coming this way must be Mr White.
That guy can’t be our teacher, for he has gone abroad.
b. 用“主语+must be doing” 表示对现在正在进行或将来正在进行的事情的推测，可翻译为 “想必正在…” “一定正在…”
They must be playing football now.
→They must be playing football now, aren’t they?
It must be raining outside.
→It must be raining outside, isn’t it?
大同古城简介According to the weather forecast, it must be snowing tomorrow.
They are going to make a film next month here. They must be looking for actors.
c. 用“主语+must have done”表示对过去发生的事情进行推测，可翻译为 “想必已经…”
eg. They must have left.
→They must have left, haven’t they?
Look at his new car. He must have earned a lot of money.( He has earned a lot of money.)
She must have come back late last night.( She came back late last night.)
→She must have come back late last night, didn’t she?
注意：用于“推测”意义时，must的否定结构通常是用can’t,(表疑问时用can,) 不可以用mustn’t. 如“can’t be”, “can’t be doing”, “can’t have done” 等表示，翻译为 “不可能”。上述的句子变为否定句时，应为：
They must have left.
→Can they have left?
→They can’t have left. 他们不可能已离开。
3）提示must和 have to的区别和用法
a. must与have to同义，但must表示说话人的主观意志，而have to却表示客观需要。
I don’t like to stay here any longer. I must leave now.
Since it is snowing, we have to stay here.
My brother is ill. I have to look after him in the hospital.
b. have to可用于较多的时态，而must一般用于现在时，其过去时常用have to的过去时had to来替换。
c. must 可作“偏偏”“硬要”
解，指令人不快的事情。
Why must it rain on Sunday?
怎么偏偏星期天下雨？
The car must break down when we were about to start off.
我们就要出发时偏偏车坏了
d. must 还可表示必然的结果。
All men must die. 人固有一死。
If you don’t hurry, you must miss the train.
3. should与ought to（一般不用于疑问句）
1)表示劝告或建议、命令，翻译为“应当，应该”
She should stay in bed for two days.
You ought to try your best to do it.
2) 表示推理、推论，可译作 “按理应当；估计”“理应；该”
< It’s nearly ven o’clock. Jack ___ be here at any moment.
A. must B. need C. should D. can
Key: C
You should arrive at the airport two hours before he goes.
广东有什么大学
3）表惊奇、怀疑、不满等情绪。 意为“竟会，竟然”。如：
eg. Why should you be so late today?
你今天怎么来得这么晚？
eg. How should I know? 我怎么会知道？
Why should I invite him?
为什么我要邀请他？
[真题再现1]
--- Yang Liwei has won great honor for our country.
--- Who is Yang Liwei?
--- What a question! It’s surprising ___, the first spaceman in China.
A. you didn’t know our national hero
B. to you not to know him
C. you should know nothing about
D. you knew nothing about him
Key: C
[真题再现2] I often e lights in that empty hou. Do you think I ______ report it to the police? (2004全国卷III)
A. should B. may C. will D. can
Key: A
[真题再现3]
—When can I come for the photos? I need them tomorrow afternoon.
—They _____ be ready by 12:00. (NMET’98)
A. can B. should C. might D. need
[点拨]选B。因顾客明天下午要用照片，所以商家理应在12点以前将照片洗出。should在此处表示“按理应当；估计”。
[真题再现4] You can’t imagine that a well-behaved gentleman _____ be so rude to a lady. (上海2001)
A. might B. need C. should D. would
[点拨] 选C。should在此句中表示惊讶。
4）表示谦逊、婉转的口气，用于提出建议，意见或请求。
I should think so. 我倒是这样想的。
I should say that it would be better to delay the meeting. 我看最好还是推迟会议。古镇周庄
I should advi you to say less and do more.
5) 用于虚拟语气
a. “should have done = ought to have done”表示本来该做的事却事实上没做。有责怪，内疚之意。
You should have told me the news yesterday. (in fact, you didn’t tell me)
I should have helped him but I was too busy.
本结构的否定形式：should not have done 表示做了不该做的事。
You shouldn’t have lent him money before.
b. 用于表示建议、命令的动词suggest, advi, order, demand, require, request, desire, ask, insist 等词的宾语从句中，谓语应由 “should+动词原形”构成。 Should可以省略。
< He suggested that I (should) accept the job.
The doctor advid that we should do more ex
ercis.
4. can 与could
1) 指能力
He is able to\can solve this problem.
My mother can u computer now.
2) 表许可(多于口语)
Can I go now?
He said I could u the computer.
You can go now.
3) 表示推测，翻译为 “可能”.多用于疑问句和否定句中, 有时也用于肯定句，表示的是逻辑上的可能性. 其肯定的推测用用 must(肯定), 用于“推测”意义时，must的否定结构通常是用“can’t be”, “can’t be doing”, “can’t have done” 等表示，翻译为 “不可能”。
< Who can he be? 他会是谁?
She can’t be waiting for you.
他不可能在等你.
He can’t have gone there alone.
他不会一个人去那里.
4) can无将来时和完成时，因此在表示将来“能够”时，需用“shall\will be able to”表示。完成时则用 “have been able to”表示。
5) can可表示“允许，请求”
You can get the reply next day.
You can reach an agreement tomorrow.
*--- Could (I u your bike)? 委婉语气
--- Yes, you can. / Yes, plea. / Yes, go ahead. / Do, plea.
No, you can’t.
企业战略管理论文
6) 在表示成功地完成某一件具体动作时，通常不用could，而用was／were able to (或managed to，succeeded in doing sth.)来表示。 但在否定句中couldn’t 和was\were not able to便不存在上述的区别。
He could solve the problem if he tried. （可能性）
He was able to solve the problem. （已解决）
He couldn’t \was not able to solve the problem.
7) 与感觉动词连用时，can，could亦可与be able to互换。
We could／were able to smell something burning in the kitchen．
5. would的用法
1) 表意愿，决心, 动作的倾向或趋向(will / would)
We invited him to the party but he wouldn’t listen.
He wouldn’t let the doctor take his blood pressure.
他不愿意让医生量他的血压。
He wouldn’t go no matter how you advid him to.
His teacher asked him not to be late again, but he wouldn’t listen.
窗子怎么也打不开。
The window wouldn’t open.
2) would在此表示过去的习惯性动作，可译为“总会”。又如：
Whenever I went to e him, he would treat me with some home-made cakes.
每次我去看他，他总是用自制的糕点招待我。3) 表示委婉地“请求，询问，建议”
Would you kindly tell me the way to the post office?
4) 表示猜测。如：
That would be in 1976, I think.
我想那大概是在1976年。
5) would和ud to
二者都可表过去时间里的习惯动作，译作“过去常常”。但也有区别
① ud to表示现在已不复存在的过去习惯动作或状态，有“今昔对比”的含义；而would只表过去经常的习惯动作，并无“今昔对比”之含义。
< I ud to have a walk after super along the river bank. (but not now)
She would worked day and night no mater what happened.
② 二者相比，would语气较强，常表一种“自愿”，而ud to仅表过去惯常
之事实，无自愿之含义。
He would spend all his money on books．
His father ud to leave for work at (but not now).
6. shall 的用法
1) 用于第二，三人称肯/否定句表示决心，命令，警告，应诺等。有“必须，可，该”的意思。
If you work hard you shall have a holiday on Saturday.(允诺)
She shall do as she is told. （命令）
He shall not come here if he doesn’t do as we tell him.（警告）
2) 在疑问句中用于第一，三人称单数表示征求意见或询问。
Shall I turn off the light? (征求意见)
Shall he wait here? (征求对方意见)
3) shall用于征求对方的意见，表示 “决心” 是情态动词。
eg: Perhaps I shall pay a visit to
England this winter
7. “情态词+完成式”用法
(1)情态词+have+过去分词
(2)情态词+have been+现在分词。
它们的用法如下：
★非推测性用法：
◆“could+完成式--- could have done”，即用于肯定句中，可以表示“本来可以完成而未完成的动作”。
-
--We could have walked to the station；it was so near．
---Yes．A taxi wasn’t at all necessary．
◆“needn’t+完成式----needn’t have done”，用于否定句中, “本来不必”，指实际上做了本来不必做的事。
There was plenty of time．She needn’t have hurried．
◆“ought to／should+完成式”，表示“本来应该”，指本应该做而实际未做的事，否定句则表示实际做了本不应该做的事。
The plant is dead，I should have given it more water.
We shouldn't have waited for her becau she never come.
◆“might+完成式”，多用于肯定句，可以表示本来可以做而实际未做的事，暗含一种责备，此时不可用may替代。
He might have given you more help，even though he was very busy.
★推测性用法：
对过去的事情进行推测时，我们可以采取“情态词+完成式”形式
◆“can／could + 完成式”表推测时多用于疑问句或否定句中，不能用于肯定句中.
He can't／couldn't have forgotten your address so soon.
Can she have lost the book?
◆“must+完成式”往往用于肯定句中，其否定形式是can't，不是mustn't(禁止).
He must have left early．(否定：He can't have left early。)
He must have been working late．(否定：He can't be working late．)
◆“may／might+完成式”表示“可能已经”，“或许已经”，是对已经发生事情的不太肯定的推测，其中may一般不用于疑问句中。
You may(might) have read about it in the papers．
He may (might) not have finished the work．
◆ 情态动词表不同的“肯定”程度，不同的“肯定”程度可按下列层次排列：
He is at home．(事实)
He must be at home．(非常可能)
He could be at home．(很可能)
He ought to be at home．(很可能)
He may be at home．(仅仅可能)
He might be at home．(或许)
He isn't at home．(事实)
He can't be home．(接近肯定)
He couldn't be at home．(不及can't肯定)
He may not be at home．(可能，但不肯定)
手机关
He might not be at home．(不及may肯定)
海阔天空粤语谐音歌词
