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2021年1月30日发(作者：汉代风云人物txt)
专四语法专题第七节：情态助动词

I.

情态助动词考点和知识要点：

———————————————————————————————————————

情态助动词概述：

情态助动词有
can (could), may (might), must, have to, shall (should, will (would), dare (dared),
need (needed), ought to
等。


情态动词无人称和数的变化；

不能单独使用，必须与其后的动词原形构成谓语。


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情态助动词知识要点：

1.

can / could
2.

may / might
3.

will, would
4.

shall
5.

should, ought to
6.

must
7.

need
8.

dare
9.

情态动词
+
不定式完成式（
have done
）


1.

can / could
1)
表示请求和允许
(Permission)


-----Can I go now?

----- Yes, you can. / No, you can
’
t.

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)
表示能力（体力、知识、技能）
(Ability)
Can you lift this heavy box?
（体力）

Mary can speak three languages.
（知识）

Can you skate?
（技能）

表示“能力”时可与
be able to
互换。

Can
只有一般现在时和一般过去式；而
be able to
则有更多的时态。

I
’
ll not be able to come this afternoon.
但当表示“经过努力才得以做成功某事”时应用
be able to
，不能用
Can
。

如：
He was able to go to the party yesterday evening in spite of the heavy rain.
3)
表示客观可能性（客观原因形成的能力）
(Possibility)


They
’
ve changed the timetable, so we can go by bus instead.


This hall can hold 500 people at least.
4)
表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。



Can this be true?

1


This can
’
t be done by him.


How can this be true?

2.

may / might




1)
表示请求和允许
(Permission)
。

might
比

may
语气更委婉，而不是过去式。否定回答时可用
can
‟
t
或
mustn
’
t
，表示“不可以，禁止”。




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



---- No, you mustn
’
t.



---- May/Might I take this book out of the room?



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





用
May I...
？征徇对方许可时比较正式和客气，而用
Can I...
？在口语中更常见。

2
）表示推测、可能性（不用于疑问句）(Possibility)
。





might
不是过去式，它所表示的可能性比
may
小。





He may /might be very busy now.




Your mother may /might not know the truth.
3)
用于祈使句，表示祝愿。





May you succeed!
4) may /might...as well
表示“不妨，还是
...
的好”
,
也可以写作
may /might as well.


Since it is raining hard, you may as well stay here.

3.

will, would


1)
用于第二人称疑问句中，表示请求、建议等，
would
更委婉，不表时态。



Will / Would you pass me the ball, please?

2)
表示意愿（
Willingness
）、 意图（
Intention
）、决心（
Determination
）、承诺 （
Promise
）
等，可用于各种人称。



I will never do that again.


They asked him if he would go abroad.

3) would
表示过去反复发生的动作或某种倾向。
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。



During the vacation, he would visit me every other day.


The wound would not heal.

4)
表示估计和猜想。

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

4.

shall


1) shall
用于第一人称，征求对方的意见。



What shall we do this evening?

2) shall
用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。



You shall fail if you don
’
t work hard.(
警告
)


He shall have the book when I finish it.(
允诺
)
He shall be punished.(
威胁
)

5.

should, ought to

2


1) should, ought to
表示“应该”，
ought to
表示义务或责任，比
should
语气重。



I should help her because she is in trouble.


You 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
。



You should / ought to go to class right away.


Should I open the window?

3)
表示推测

should , ought to (
客观推测
), must(
主观推测
)
。



He must be home by now. (
断定他已到家
)


He ought to/should be home by now.(
不太肯定
)


This is where the oil must be.(
直爽
)
This is where the oil ought to/should be.(
含蓄
)


Uncertain








might


























may



















could




















can



















should


















ought to



















would




















will
Certain










must



6.

must, have to




1)
表示必须、必要。



You must come in time.


在回答引出的问句时，如果是否定的，不能用
mustn< br>’
t
（禁止，不准），而用
needn
’
t, don
’
t have to
（不必）
.


---- Must we hand in our exercise books today?


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




2) must
是说话人的主观看法，

而
have to
则强调客观需要。
Must
只有一般现在时，

have
to
有更多的时态形式。





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




I had to work when I was your age.




3)
表示推测、可能性（只用于肯定的陈述句）






You
’
re Tom
’
s good friend, so you must know what he likes best.





Your mother must be waiting for you now.

7.

dare, need




1) dare
作情态动词用时
,
常用于疑问句、否定句和条件从句中
,
过去式形式为
dared
。





How dare you say I
’
m unfair?




He daren
’
t speak English before such a crowd, dare he?




If we dared not go there that day
，

we couldn
’
t get the beautiful flowers.


2) need
作情态动词用时
,
常用于疑问句、
否定句。
在肯定句中一般用
must, have to, ought
to, should
代替。


3



You needn
’
t come so early.



---- Need I finish the work today?




---- Yes, you must. / No, you needn
’
t.




3)
dare
和

need
作实义动词用时，

有人称、时态和数的变化。在肯定句中，
dare
后面
常接带
to< br>的不定式。在疑问句和否定句中，
dare
后面可接带
to
或不带to
的不定式。
而
need
后面只能接带
to
的不定式 。





I dare to swim across this river.




He doesn
’
t dare (to) answer.




He needs to finish his homework today.





8.

will, would


1)
用于第二人称疑问句中，表示请求、建议等，
would
更委婉，不表时态。



Will / Would you pass me the ball, please?

2)
表示意愿（
Willingness
）、 意图（
Intention
）、决心（
Determination
）、承诺 （
Promise
）
等，可用于各种人称。



I will never do that again.


They asked him if he would go abroad.

3) would
表示过去反复发生的动作或某种倾向。
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。



During the vacation, he would visit me every other day.


The wound would not heal.

4)
表示估计和猜想。



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








9.

情态动词
+
不定式完成式（
have done
）




1) can / could + have done
在肯定句中表示
“本来可以做而实际上能做某事”
，是虚拟语气 ；
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.
（虚拟语气）



He can
’
t have been to that town.
（推测）



Can he have got the book?
（推测）


2) may / might +
不定式完成式（
have done
）



表示对过去行为的推测。不能用于疑问句中，没有虚拟语气的用法。
Might所表示的可
能性比
may
小。



He may not have finished the work .
If we had taken the other road, we might have arrived earlier.


3
）
must +
不定式完成式（
have done
）



用 于肯定句中，表示对过去行为的推测。意为“一定、想必”。其疑问、否定形式用
can
，can
’
t
代替。参看
1) can / could + have done
表示推测。



You must have seen the film Titanic.


He must have been to Shanghai.
4
）
should +
不定式完成式（
have done
）




用于肯定句中，表示对过去行为的推测。




He should have finished the work by now
。


4



表示“本应该做而实际上没有做某事”，其否定式表示某种行为本不该发生却发生了

可以与
ought to +
不定式完成式（
have done
）互换。



You ought to / should have helped him. (but you didn
’
t.)


She shouldn
’
t have taken away my measuring tape, for I wanted to use it.
5) needn
’
t +
不定式完成式（
have done
）



表示“本来不必做而实际上做了某事”。



You needn
’
t have watered the flowers, for it is going to rain.

6) will +
不定式完成式（
have done
）



主要用于第二、三人称，表示对已完成的动作或事态的推测。

He will have arrived by now.

II.

情态助动词专四真题模拟题


1.

Among the four sentences below, Sentence _____ expresses the highest degree of possibility.
A. It may take a long time to find a solution to the problem.
B. It might take a long time to find a solution to the problem.
C. It could take a long time to find a solution to the problem.
D. It should take a long time to find a solution to the problem.

2.

Which of the following italicized words does NOT indicate willingness?
A. What
will
you do when you graduate?
B. They
will
be home by now.
C. Who
will
go with me?
D. Why
will
you go there alone?

3.

When the sentence “Shall I drive you to the airport first?” is turned into indirect sp
eech,
which of the following is most appropriate?

A.

He agreed to drive me to the airport first.








B.

B. He offered to drive me to the airport first.



C. He advised me to go to the airport first.









D. He suggested that I drive to the airport first.

4.

Which of the following sentences indicates POSSIBILITY?
A. The moon cannot always be at the full.
B. You cannot smoke inside the building.
C. He cannot come today.
D. She cannot play the piano.

5.

Which of the following sentences a fact?



A. Mary and her son must be home by now.



B. Careless reading must give poor results.



C. He must be working late at the office.
D
．
It‟s getting late, and I must leave now.



5

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