情態動詞的用法總結
下面是小編整理的一些關於情態動詞的用法總結，歡迎大家閱讀!
possibility: can / could, may / might
certainty: must, will, should
ability: can / could, be able to
permission: can / could, may / might
requests: can / could, will / would
suggestions: could / may /might, shall
necessity: must, have to, have got to, need
advice: ought to, had better
情態動詞的語法特徵
1. 情態動詞沒有人稱和數的變化,即情態動詞第三人稱單數不加- s (have to, have got to, be able to 除外)。
2. 情態動詞不能表示正在發生或已經發生的事情,只表示期待或估計某事的發生。
3. 情態動詞本身具有一定詞義, 但意思不夠完整, 不能單獨做謂語, 後接動詞原形一起構成謂語部分 (ought to, have to/have got to, be able to除外)。
4. 情態動詞無非謂語形式,即無不定式、分詞等形式。
Sum up
1. can和be able to
1) can (could) 表示能力、可能, 只用於現在式和過去式
2) be able to可以用於各種時態。
只用be able to的情況：
a. 位於助動詞後。
b. 情態動詞後。
c. 表示過去某時刻動作時。
d. 用於句首表示條件。
e. 表示成功地做了某事時,只能用was/ were able to,不能用could。
注意:could還可不表示時態,只表示
1) 提出委婉的請求,回答中不可用could。
--- Could I have the television on?
--- Yes, you can. / No, you can’t.
2) 在否定、疑問句中表示推測或懷疑。
He couldn’t be a bad man.
2. may和might
1) 表示允許或請求;表示沒有把握的推測;may 放在句首,表示祝願。
e.g. May God bless you!
He might be at home.
注: might 表示推測時,不表示時態。只是可能性比may 小。
2) 成語:may/might as well,後面接不帶to 的不定式，意爲"不妨"。
e.g. If that is the case, we may as well try.
3. have to和must
1) 兩詞都是“必須”的意思, have to 表示客觀的需要, must 表示說話人主觀上的看法, 即主觀上的必要。
e.g. My brother was very ill, so I had to call the doctor in the middle of the night.
He said that they must work hard.
2) have to有人稱、數、時態的變化,而must只有一種形式。但must可用於
間接引語中表示過去的必要或義務。
e.g. He had to look after his sister yesterday.
3) 在否定結構中：don’t have to 表示“不必”; mustn’t表示”禁止”。
e.g. You don’t have to tell him about it. 你不必把這事告訴他。
You mustn’t tell him about it. 你不能把這事告訴他。
4. 情態動詞must表示推測
1) must用在肯定句中表示較有把握的推測,意爲“一定”。
2) must表對現在的狀態或現在正發生的事情的推測時, 後面通常接系動詞be的原形或行爲動詞的進行時。
e.g. You have worked hard all day.
You must be tired.(對現在情況的推測判斷)
He must be working in his office. 他一定在辦公室工作呢。
比較: He must be staying there. 他現在肯定呆在那兒。 表推測
He must stay there. 他必須呆在那兒。不表推測
3) must 表示對已發生的事情的推測時, 要接完成時。
e.g. I didn’t hear the phone. I must have been asleep.
4) must表示對過去某時正發生的事情的推測, 後面要接不定式的完成進行時。
e.g. ---Why didn’t you answer my phone call?
---Well, I must have been sleeping, so I didn’t hear it.
5) 否定推測用can’t.
e.g. If Tom didn’t leave here until five o’clock, he can’t be home yet.
5.情態動詞表示推測的用法
can, could, may, might, must 皆可表
示推測,其用法如下：
1) 情態動詞+動詞原形,表示對現在或將來的情況的推測,此時動詞通常爲系動詞。
e.g. I don’t know where she is. She may be in Wuhan.
2) 情態動詞+動詞進行時, 表示對現在或將來正在進行的情況進行推測。
e.g. At this moment, our teacher must be correcting our exam papers.
3) 情態動詞+動詞完成時, 表示對過去情況的推測。
e.g. The road is wet. It must have rained last night.
4) 情態動詞+動詞的完成進行時, 表示對過去正在發生事情的推測。
e.g. Your mother must have been looking for you.
5) 推測的否定形式,疑問形式用can’t, couldn’t表示。
e.g. Mike can’t have found his car, for he came to work by bus this morning.
注: could, might表示推測時不表示時態,其推測的肯定程度不如can, may。
6.情態動詞+have+過去分詞
1) may (might) have + done sth., can (could) have + done sth. 表示過去,推測過去時間裏可能發生的事情。
e.g. Philip may (might) have been hurt seriously in the car accident.
Philip can (could) have been hurt seriously in the car accident.
2) must have+done sth., 表示對過去時間裏可能發生的事情的推測,語氣較強,具有“肯定”的意思。
e.g. --- Linda has gone to work, but her bicycle is still here.
--- She must have gone by bus.
3) ought to have done sth.should have done sth.本應該做某事,而事實上並沒有做; 否定句表示“不該做某事而做了”。
e.g. You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.(事實上已扔了。)
注: ought to 在語氣上比should 要強。
4) needn’t have done sth. 本沒必要做某事
e.g. I dressed very warmly for the trip, but I needn’t have done so. The weather was hot.
5) would like to have done sth. 本打算做某事
e.g. I would like to have read the article, but I was very busy then.
7. 情態動詞should和ought to
should 和ought to 都爲“應該”的意思,可用於各種人稱。
e.g. --- Ought he to go?
--- Yes. I think he ought to.
表示要求,命令時,語氣由 should(應該)、(had better最好)、must(必須) 漸強。
8. 情態動詞had better表示“最好”
had better 相當於一個助動詞,它只有一種形式,它後面要跟動詞原形。
had better (not) do sth.
e.g. It is pretty cold. You’d better put on my coat.
She’d better not play with the dog.
had better have done sth.
表示與事實相反的結果,意爲“(過去)本來最好”。
e.g. You had better have come earlier.
9. 情態動詞would rather表示“寧願”
would rather (not) do
would rather…than…寧願…而不願
would sooner had rather had sooner表示"寧願"、"寧可"的意思。
e.g. If I have a choice, I had sooner not continue my studies at this school.
10. will和would
1) would like to do = want to 想要
e.g. Would you like to go with me?
2) Will you…? / Would you like…?
表示肯定含義的請求勸說時,疑問句中一般用some, 而不是any。
e.g. Would you like some cake?
3) 否定結構中用will, 一般不用would, won’t you是一種委婉語氣。
e.g. Won't you sit down?
11. need和dare
這兩詞既可做實義動詞用,又可做情態動詞用。作爲情態動詞,兩者都常用於疑問句,否定句和條件句。並注意回答用need 提問的句子時，肯定回答用must。
need 作實義動詞時後面的不定式必須帶to,而dare作實義動詞用時, 後面的to時常可以被省略。
1) 實義動詞: need+ n. / to do sth.
2) 情態動詞: need,只用原形need後加do,否定形式爲need not.
e.g. ---- Need you go yet?
---- Yes, I must. / No, I needn't.
3) need, want, require, worth(形容詞)後面接doing也可以表示被動。
need doing = need to be done
Exercises
1. A left-luggage office is a place where bags ____be left for a short time, especially at a railway station.
A. should B. can
C. must D. will (B)
2. How ___ you say that you really understand the whole story if you have covered only part of the article?
A. can B. must
C. need D. may (A)
3. — The room is so dirty. ___we clean it?
— Of course.
A. Will B. Shall C. Would D. Do (B)
4. My English-Chinese dictionary has disappeared. Who ___ have taken it?
A. should B. must
C. could D. would (C)
5. — Is John coming by train?
— He should, but he ____ not. He likes driving his car.
A. must
C. need (D)
6. — I heard they went skiing in the mountains last winter.
— It ____ true because there was little snow there.
A. may not be B. won’t be
C. couldn’t be D. mustn’t be (C)
7. It has been announced that candidates __ remain in their seats until all the paper have been collected.
A. can B. will C. may D. shall (D)
8. — I hear you’ve got a set of valuable Australian coins. ___ I have a look?
—Yes, certainly.
A. Do B. May C. Shall D. shall (B)
9. Oh, I’m not feeling well in the stomach, I ___ so much fried chicken just now.
A. shouldn’t eat
B. mustn’t have eaten
C. shouldn’t have eaten
D. mustn’t eat (C)
10. 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 (B)
