情态动词的基本用法 知识点
情态动词有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。
一、 can, could
1. 表示能力(体力、知识、技能)。
例如:①Can you lift this heavy box?你能举起这个重箱子吗?
②Mary can speak three languages.Mary can speak three languages.
此时可用be able to代替。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。
例如:I'll not be able to come this afternoon.我今天下午不能来了。
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。
例如:He was able to go to the party yesterday evening in spite of the heavy rain.尽管下着大雨,他还是去参加了昨晚的聚会。
2. 表示请求和允许。
例如:—Can I go now?— Yes, you can. / No, you can't.——我现在可以走了吗? ——可以,你可以的/不,你不能。
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。
例如:— Could I come to see you tomorrow?— Yes, you can. ( No, I'm afraid not. )——我明天能来看你吗?——可以,(不,恐怕不行。)
3. 表示客观可能性(客观原因形成的能力)。
例如:①They've changed the timetable, so we can go by bus instead.他们改变了时间表,所以我们可以改乘公共汽车。
②This hall can hold 500 people at least.这个大厅至少可以容纳500人。
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。
例如:①Can this be true?这是真的吗?
②This can't be done by him.他可能做不到的。
二、 may, might
1. 表示请求和允许。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”。
例如:①—Might/ May I smoke in this room?我可以=在屋里吸烟吗?— No, you mustn't你一定不要抽烟。
②— May/Might I take this book out of the room?我能把这本书拿出房间吗?— Yes, you can. (No, you can't / mustn't. )可以(不行)。
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.用于祈使句,表示祝愿。
例如:May you succeed!祝你成功!
3.表示推测、可能性(不用于疑问句)。might不是may的过去式,它所表示的可能性比may小。
例如:①He may /might be very busy now.现在他可能比较忙。
②Your mother may /might not know the truth.你的妈妈可能不知道真相。
三、 must, have to
1. 表示必须、必要。
例如:You must come in time.你必须及时赶到。
在回答引出的问句时,如果是否定的,不能用mustn't“禁止,不准”,而用needn't, don't have to“不必”。
例如:— Must we hand in our exercise books today?我们今天一定要交练习本吗?— Yes, you must.是的。—— No, you don't have to / you needn't.没必要。
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。
例如:①The play isn't interesting, I really must go now.这出戏不好玩,我真的得走了。
② I had to work when I was your age.我像你这么大的时候还得工作。
3.表示推测、可能性(只用于肯定的陈述句)。
例如:① You're Tom's good friend, so you must know what he likes best.你是汤姆的好朋友,所以你一定知道他最喜欢什么。
②Your mother must be waiting for you now.你你母亲现在一定在等你。
四、 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。
例如:①How dare you say I'm unfair?你怎么敢说我不公平?
② He daren't speak English before such a crowd, dare he?他不敢在这么多人面前说英语,是吗?
③ If we dared not go there that day, we couldn't get the beautiful flowers.如果那天我们不敢去那里,我们就得不到那些美丽的花。
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。
例如:①You needn't come so early.你没必要来这么早。
② —Need I finish the work today?——需要我今天完成工作吗?—Yes, you must. / No, you needn't.——是的,你必须完成/没必要。
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。
例如:① I dare to swim across this river.我敢游过这条河。
② He doesn't dare (to) answer.他不敢回答。
③ He needs to finish his homework today.他今天必须完成作业。
五、 shall, should
1.shall 用于第一人称,征求对方的意见。
例如:What shall we do this evening?今晚我们做什么?
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。
例如: ①You shall fail if you don't work hard.如果你不努力,你就会失败。(警告)
② He shall have the book when I finish it.当我完成这本书的时候,他会得到这本书。(允诺)
③ He shall be punished.他应该受到惩罚。(威胁)
六、 will, would
1. 表示请求、建议等,would更委婉。
例如:Will / Would you pass me the ball, please? 你能把球传给我吗?
2. 表示意志、愿望和决心。
例如:① I will never do that again.我再也不会那么做了。
② They asked him if he would go abroad.他们问他是否愿意出国。
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。
例如:①During the vacation, he would visit me every other day.假期期间,他每隔一天来看我一次。
② The wound would not heal.伤口无法愈合。
4.表示估计和猜想。
例如:It would be about ten o'clock when she left home.她离开家的时候大概是十点。
七、 should, ought to
1. should, ought to表示“应该”,ought to表示义务或责任,比should语气重。
例如:① I should help her because she is in trouble.我应该帮她,因为她有麻烦了。
② You ought to take care of the baby.你应该好好照顾孩子。
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。
例如:① You should / ought to go to class right away.你应该立刻去上课。
② Should I open the window?我应该打开窗户吗?
3.表示推测。should , ought to (客观推测), must(主观推测)。
例如:①He must be home by now.现在他肯定在家。 (断定他已到家)
②He ought to/should be home by now.现在他应该在家。(不太肯定)
③ This is where the oil must be.这里一定有石油。(直爽)
④This is where the oil ought to/should be.这里应该有石油。(含蓄)
八、 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。
例如:① You could have done better, but you didn't try your best. 你本可以做得更好,但你没有尽力。(虚拟语气)
② He can't have been to that town.他不可能去过那个小镇。(推测)
③ Can he have got the book?他能拿到那本书吗?(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。
例如:① He may not have finished the work .他可能还没完成任务。
② If we had taken the other road, we might have arrived earlier.如果我们走另一条路,我们可能会早点到达。
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。
例如:① You must have seen the film Titanic.你一定看过电影《泰坦尼克号》。
② He must have been to Shanghai.他一定去过上海。
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。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。
例如:①He should have finished the work by now.他现在应该已经完成工作了。
② You ought to / should have helped him. (but you didn't.)你本应该去帮助他(实际上没有)。
③ She shouldn't have taken away my measuring tape, for I wanted to use it.她不该拿走我的卷尺,因为我想用它。
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”。
例如:You needn't have watered the flowers, for it is going to rain.你不必浇这些花,因为要下雨了。
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。
例如:He will have arrived by now.他现在应该到了。
情态动词的基本用法 知识点题库
If you __ go, at least wait until the storm is over.
A . can
B . may
C . must
D . will
You _______ feel all the training a waste of time, but I'm a hundred percent sure later you'll be grateful you did it.
A . should
B . need
C . shall
D . may
请用适当情态动词填空,每空一词。
-
(1)
In those days on winter evenings, we all sit around the fire, chatting.
-
-
(2)
Your sister has been admitted to Beijing University? She be quite clever!
-
-
(3)
You haven't finished your paper? But you have finished it by the end of last week!
-
-
(4)
I promise if you win the football game, all of you have a chance to travel in Paris for free.
-
–Mummy, the toy advertised on TV is really fantastic. Will you buy me one?
--OK. You __________ have one if you behave well.
A . might
B . must
C . could
D . shall
According to the school rule, no student ________ go out during the class without the teacher's permission.
A . could
B . need
C . shall
D . would
You ____ be Carol. You haven't changed a bit after all these years.
A . must
B . can
C . will
D . shall
Nothing is wasted
and everything ,even plastic bags, can be(回收).
I
would a it if you could pay in cash.
You should (apology) to your teacher for coming late.
She knew she was wrong, but she ________ tell him.
A . dare not to
B . dare
C . dares not
D . dare not
There is a great noise in their room.
The couplebe still quarreling at this time.
— Can't you
stay a little longer?
— It's
getting late. I really go now, my daughter is home alone.
—Did you
(buy) the film tickets yesterday?
—Yes, I (buy) two. I can (give) one to you.
I knew she be in because I heard the radio, but she didn't open the door.
With luck, tomorrow (can/could) be a cooler day.
My father's birthday is coming. What (shall/may) I give him?
Why don't you try on this dress? It (will/can) look nice on you.
I have hurt your feelings, but it was not my
intention.
Children under 10
years of age be under adult supervision when entering the museum.
—Mummy, I would really like a laptop.
—You get a laptop as long as you pass your entrance examination.