Grammar. Grammar. 情态动词用法. 情态动词的语法特征 情态动词有一定的意义，表示或暗示某种情绪或 态度，表示可能、建议、愿望、必要、允许、能力等。 2. 情态动词没有人称和数的变化，即不随主语的不同而变化。 3. 情态动词不能独立使用，必须和实义动词一起构成谓语。 4. 情态动词除 ought 和 have 外，后面只能接不带 to 的不定式。 5. 情态动词没有非谓语形式，即没有不定式、分词等形式。. 只作情态动词的 can / could, may /
只作情态动词的 can / could, may /
might, ought to, must
可情态可实义的 need, dare
可情态可助动词的 shall / should, will /
相当于情态动词的 have to, used to
1.must用于一般问句中,肯定回答用must否定式用 needn’t或don’t have to，做 “不必”, mustn’t表示“禁止，不允许”
— Must I finish all assignments at a time?
—Yes, you must.
No, you needn't.
2.表示“必须”这个意思时，must 和have to 稍有区别。must着重说明主观看法，have to 强调客观需要。另外，have to 能用于更多时态。
I don’t like this TV set. We must buy a new one. There was no more bus. They had to walk home.
3.must表示对某人某事的猜测, 作“准是”, “一定” , 一般用于肯定句中。对过去发生的事情作肯定判断用must have done
Youmust be the new teacher.
He must be joking. There is nobody here. They must have all gone home.
4. must表示“偏要, 硬要”, 指做令人不快的事情
He must come and worry her with question, just when she was busy cooking the dinner. Of course，after I gave her my advice，she must go and do the opposite.
Can you speak Japanese?
He can’t be at home now.
Can I have a look?
How can you be so rude?
can表示“能够”时与短语be able to同义，但can只用于一般现在时或过去时，而后者可用于各种时态。另外，can表示个人有某种能力，而be able to表示某人通过努力、克服困难做成某事，相当于succeed in doing sth.；叙述过去事实时，最好用was / were able to，因为could只表示过去具有某种能力。
can / could + have done在肯定句中表示“本来可以做而实际上没做某事” ；在疑问句或否定句中表示对过去行为的怀疑或不肯定,表示推测。 You could have done better, but you didn’t try your best. 你本来可以做得更好，但你没努力。
He can’t have been to that town.
It may be true.
May I ask you a question?
May you be happy all your life.
might 比 may 语气更委婉
might / may have done表示对过去发生的动作进行的可能性推测。
He may have gone to the clinic.
He might have read about the news in the newspaper.
Go where you will.
She asked if I would go with them.
Would Sunday night suit you?
Will / Would you please post the letter for me?
Oil will float on water.
When he was a child, he would often go skiing.
4. 表示预料或猜想will用于谈论现在，would可用于谈论过去，也可用于谈论现在(语气较委婉)。Ask him. He will know. Every family would have some sort of trouble. I thought you would have finished it by now.
You shall do as I say. (命令)
Nothing shallstop me doing it. (决心)
Tell him that he shall have the book tomorrow. (允诺)
Shall I open the window for you？（征求意见）
Shall he fetch some water for you？（请求）
Young people should learn how to use computers.
4. should have done表示责备或批评,意为“本应该…但”
You should have told her the truth earlier.
She shouldn’t have left without saying a word.
5. should用于可能性推测时, 表“应该，很可能”
They left at 5:30. Theyshouldget there now.
1. — Shall I inform him of the change of the
schedule right now?
— I am afraid you _______, in case he
comes late for the meeting. （2011 福建）
A. will B. must C. may D. can
解析：根据下句后半部分“以免他开会迟到”，可知是告诉上句说话人“你必须立刻告诉”，故答案为B。本句的意思是：--- 我应该立刻通知他安排的变化吗？--- 恐怕你得立刻告诉他，以免他开会迟到。
— Don’t worry. He come. He said he
wasn’t certain what his plans were.
A. must not B. need not
C. would not D. might not
解析：根据语境“他说他不太确定他的计划是什么”可知 “他可能不会来”。must not“不准”；need not“不必”；would not“不会”；might not“可能不”。
3. Jack described his father, who ____ a brave boy many years ago, as a strong–willed man. （2010 安徽卷）
A. would be B. would have been
C. must be D. must have been
解析：句意为“杰克把他的父亲描述为一个意志坚强的人，他的父亲多年前肯定很勇敢”用must have been表示对过去事情的肯定推测。
4. You _____ buy a gift, but you can if you want to. years ago, as a strong–willed man. （2010 湖南卷）
A. must B. mustn't
C. have to D. don't have to
解析：don’t have to 意为“没有必要”，符合语境，句意为：“你没有必要买礼物，但如果你想买的话，你也可以买。”
5. I have told you the truth. ______ I keep years ago, as a strong–willed man.
repeating it? （2010 江西卷）
A. Must B. Can
C. May D. Will
解析： must 必须, 一定 can 可以, 能够， may 也许，will 意愿, 倾向性动作。前半句说我告诉你事实了, 这里用的是现在完成时, 表示过去的动作对现在造成了影响, 既然我已经说了, 我还必须重复一遍吗？
6. I_______ have watched that movie — years ago, as a strong–willed man.
it’ll give me horrible dreams. （2010山
A. shouldn’t B. needn’t
C. couldn’t D. mustn’t
解析：句意应为“我本来不应该看那部电影的----它会使我做噩梦的。”表示“本来不应该做而做了某事”用shouldn’t have done, 所以A项正确。
Choose the best answers. years ago, as a strong–willed man.
5. We hope that as many people as possible years ago, as a strong–willed man.
_____ join us for the picnic tomorrow. A. may B. must C. should D. can6. — I think I’ll give Bob a ring. —You _____. You haven’t been in touch
with him for ages. A. will B. may C. would D. should7. — Could I have a word with you, Mum? — Oh dear, if you ______. A. can B. must C. may D. should
8. years ago, as a strong–willed man. It is usually warm in my hometown in March,
but it _____ be rather cold sometimes.
A. must B. can C. should D. would
9. You don’t have to know the name of the
author to find a book. You _____ find the
book by the title.
A. must B. need C. can D. would
10. Although this ____ sound like a simple task, great care is needed.
A. must B. may C. shall D. should
11. You ______ be hungry already — you had years ago, as a strong–willed man.
lunch only two hours ago!
A. wouldn’t B. can’t
C. mustn’t D. needn’t
12. According to the air traffic rules, you ___
switch off your mobile phone before
A. may B. can C. would D. should
13. She ______ have left school, for her bike is
A. can’t B. wouldn’t
C. shouldn’t D. mustn’t
Complete the following sentences using modal verbs. years ago, as a strong–willed man.
5. My father’s birthday is coming. What years ago, as a strong–willed man.
_____ I get him?
6. Why don’t you try on this dress? It _______
look nice on you.
7. --- Who was the man talking with your
--- I’m not sure. It ______ be her brother.
8. I don’t know when the guests be here. They
_________ arrive at any time.
will / could
Homework years ago, as a strong–willed man.
1. Finish the exercises in
Discovering Useful Structure.
2. Finish exercises in Using
Structures in Workbook.