Modal Verbs情態(tài)動詞

學習目標：學生學會can, could, may, might, will, would, shall, should, must, mustn’t的用法

一、情態(tài)動詞的特征

1．有一定的詞義，但不能單獨作謂語，它們要和行為動詞或連系動詞連用，構成謂語。

2．沒有人稱和數(shù)的變化，主語是第三人稱單數(shù)時，情態(tài)動詞的形式不發(fā)生變化。

We/He must work hard．

3．后面接原形動詞，即不帶to的不定式（ought to, have to, used to本身帶有to)。如：

He may lose his way． / You ought to obey the law．你要遵守法律。

4．具有助動詞的作用，即可用來構成否定句、疑問句及用于簡明答語。

二．情態(tài)動詞用法要點

㈠ can (could)

⒈ 表示能力，could主要指過去時間。

①Can you lift this heavy box?

②Mary can speak three languages.

③Could the girl read before she went to school?

⒉ 表示客觀可能（理論上或是邏輯判斷上）。

①The temperature can fall to –60℃, that is 60℃ below freezing.

②Accidents can happen at any time.

③It can be interesting to go out for a walk.

⒊ 表示請求允許。

①He asked whether he could take the book out of the reading-room.

②---Can I have a look at your new pen?

--- Yes, you can. / No, you can’t.

此時可與may互換。在疑問句中還可用could, might代替，不是過去式，只是語氣更委婉，不能用于肯定句和答語中。

⒋ 表推測。用于否定句、疑問句。（表驚異、懷疑、不相信等態(tài)度。）

①You could have done better, but you were too careless.

② I saw Mr. Wang just now. He couldn’t have gone toGermany.

③He can’t (couldn’t) be over sixty. 他不可能超過六十歲。

⒌ 當表示“經(jīng)過努力才得以做成功某事”時應用be able to，不能用can。如：

He was able togo to the party yesterday evening in spite of the heavy rain.

㈡ may (might)

1表示請求和允許。might比 may語氣更委婉，而不是過去式。

肯定回答：Yes, please. / Certainly.

否定回答：No, you mustn’t /can’t , / Please don’t ./ You’d better not.

----Might/ May I smoke in this room?

---- Yes, you can. (No, you can’t / mustn’t. )

注意：用May I...？征徇對方許可時比較正式和客氣，而用Can I...？在口語中更常見。

2 表示推測、可能性（不用于疑問句）。

might不是過去式，它所表示的可能性比may小。

①He may /might be very busy now.

②Your mother may /might not know the truth.

3 may 放在句首，表示祝愿

①May God bless you! ② May you succeed!

4.may/might as well 動詞原形， '不妨，最好，滿可以，倒不如'。相當于had better

①You may as well do it at once． ②We may as well stay where we are．

㈢ must

⒈ 表示必須、必要。 You must come in time.

注意答語： --- Must we hand in our exercise books today?

--- Yes, you must.

--- No, you don’t have to / you needn’t.

mustn’t 表示明令禁止，“千萬別，不許，一定不要”

You mustn’t play with fire.

⒉表示推測、可能性（只用于肯定的陳述句）

①He must be ill. He looks so pale.

②Your mother must be waiting for you now.

③It must have rained last night, for the ground is wet.

⒊must 意為“偏偏，偏要，硬要”做某事，指的是做令人不愉快的事情。

①Must you shout so loudly?

②---How old are you，madam?

---If you must know，I’m twice my son’s age.

⒋ 對比 must 和 have to

must是說話人的主觀看法， 而have to則強調(diào)客觀需要。

must只有一般現(xiàn)在時， have to 有更多的時態(tài)形式。

① The play isn’t interesting, I really must go now.

② I had to work when I was your age.

㈣ will

⒈ 表意愿，愿望，決心。

①If you will read the book, I’ll lend it to you.

②I will do anything for you.

⒉ 表請求，建議對方做某事。用于疑問句，與第二人稱連用。

①Will you close the window? It’s a bit cold.

②Won’t you drink some more coffee? 再來一點咖啡好嗎？

⒊ 表示某種傾向或習慣性動作。

①Oil will float on water.

②Fish will die out of water. 魚離開水就不能活。

③The door won’t open. 這門打不開。

④The boy will sit there hour after hour looking at the traffic go by.

㈤ would

1. would表示過去反復發(fā)生的動作或某種傾向。would表示過去習慣時比used to正式，且沒有“現(xiàn)已無此習慣”的含義。

①Every time she was in trouble, she would go to him for help.

②The wound would not heal.

2. 表示估計和猜想。

It would be about ten o’clock when she left home.

3.表意愿。

Would you like some cake? （表示肯定含義的請求勸說時）

I said I would do anything for you. 我說過我愿意為你做任何事。

4.表委婉地提出請求、建議或看法。

Would you mind cleaning the window? 請把窗戶擦一下好嗎？

㈥ shall

⒈ shall 用于第一人稱，表示提議或征求意見。

Shall I turn on the lights? / What shall we do this evening?

⒉ shall 用于第二、三人稱，表示說話人給對方的命令、警告威脅、允諾或決心。

① You shall fail if you don’t work hard. 表示：________

②He shall have the book when I finish it. 表示：_______

③You shall do as I say. 表示：_______

④Nothing shall stop us from carrying out the plan. 表示：_______

3. 表示宣布法律或規(guī)定。

According to the rules, each competitor shall wear a number over the race.

典型例題

1. -----I'm sorry. I _________ at you the other day.

-----Forget it. I was a bit out of control myself.

A. shouldn't shout B. shouldn't have shouted

C. mustn't shout D. mustn't have shouted

2. John promised his doctor he _________ not smoke, and he has never smoked ever since.

A. might B. should C. could D. would

3. Tom, you _____ leave all your clothes on the floor like this.

A. can't B. mustn’t C. shouldn't D. needn't

4. --- What does the sign over there read?

--- “No person ______ smoke or carry a lighted cigarette in this area.”

A. may B. can C. shall D. should

5.---What’s the name?

---Khulaifi. _________ I spell that for you?

A. Shall B. Would C. Should D. Can

6. It is usually warm in my hometown in March, but it _________ be rather cold sometimes.

A. must B. can C. should D. would

7. Johnny，you ________ play with the knife，you ______ hurt yourself.

A. won't；can't B. mustn't；may C. shouldn't；must D. can't；shouldn't

8.--- Cathy, I have cleaned the room for you.

---Thanks. You _____ it. I could manage it myself.

A. mustn’t to B. needn’t do C. needn’t have done D. shouldn’t have done

9. Peter _______ be really difficult at times even though he's a nice person in general.

A. shall B. should C. can D. must

10. You _________ be hungry already----you had lunch only two hours ago!

A. wouldn't B. can't C. mustn't D. needn't

11.I was really anxious about you. You ________ home without a word.

A. mustn't leave B. shouldn't have left C. couldn't have left D. needn't leave

12.--- Tom came to work last Friday, but no one has seen him since.

--- ________ he have had an accident ?

A. Should B. Must C. Might D. Could

13.--- It’s the office! So you _______ know eating is not allowed here.

--- Oh, sorry.

A. must B. will C. may D. need

14.Although he was badly hurt, he _____ explain what had happened.

A. could B. might C. was able to D. couldn’t

15. Peter ___come with us tonight, but he isn't very sure yet.

A. must B. may C. can D. will

答案：

BDBCA BBCCB BDACB