高中英语情态动词用法解析
常用情态动词：can could表示能力/may,might, can,could表示许可/must表示必须/should,ought to表示应该/must,may,might表示推测语气
shall/will,would/need/had better的用法
1. can/could表示能力
1） can/could表示具有某种能力
I can sing many English songs.
我会唱许多英语歌曲。
Can you ride a horse?
你会骑马吗?
She could play the piano at the age of five.
她五岁就会弹钢琴。
He couldn't swim when he was young.
他年轻时不会游泳。
2）be able to（能够），与can/could同义，但较之can/could，be able to可以用于各种时态。比如：
He is able to draw Chinese paintings.
他会画国画。
We have been able to talk with each other in English.
我们已经能够用英语相互交流了。
They will soon be able to repair a motorbike.
他们很快就会修理摩托车了。
3）was/were able to表示过去一次特定的能力，即表示在某特定场合设法成功做某事，相当于managed to do sth.，此时不能用could。比如：
We were able to return to our campsite before the storm.
我们在暴风雨前设法回到营地。
He was able to save the child in the water.
他设法救起了水中的孩子。
但在否定结构中两者没有区别。比如：
She wasn't able to/couldn't find her lost watch.
她找不到遗失的手表。
2.may/might, can/could表示许可
（1）may/might, can/could可以表示许可某人做某事。比如：
You may/can sit here and wait for him.
你可以坐在这儿等他。
You may/can finish your papers at home.
你们可以在家完成这些试卷。
He said that the students might/could take the books home.
他说学生们可以把那些书带回家去。
（2）May/Might/Can/Could I…?表示请求对方许可，其中may/might语气比较正式，而can/could语气较为随便，could的语气最为婉转。比如：
——May/Might/Can/Could I take a seat beside you?
我可以坐在你旁边吗?
——Yes, you may/can.
可以。
——No, you may not/can't.
不可以。
上述回答中一般不用might/could。
（3）may not, can't, mustn't都可以表示不许可。比如：
You may not/can't sit in this waiting room. It's for old people only.
你们不可以坐在这个候车室。这是专供老人坐的。
Visitors mustn't touch the paintings at eh exhibition.
参观者不准触摸展览会上的画。
3. must表示必须
（1）must可以表示必须。比如：
You must finish all these exercises after school.
放学后你们必须完成所有这些练习。
Every one of you must hand in a book report next week.
下周你们每个人必须交一份读书报告。
（2）Must…? 用于询问"是否必须做某事"。
注意：其否定回答为needn't不必。比如：
——Must we be here before eight tomorrow morning?
我们必须上午八点前到这儿吗?
——Yes, you must.
是的，必须。
——No, you needn't/don't have to/don't need to.
不，不必。
（3）表示"不必"可以用结构needn't, don't need to, don't have to。比如：
If you already have this book, you don't have to/needn't/don't need to buy another one.
如果你已经有了这本书，不必再买一本。
注意：与mustn't（不准）的意义区别：
You needn't do that exercise since you understand it.
既然懂了你就不必做那个练习。
You mustn't do such a thing again.
你不准再干这样的事。
（4）must与have to的区别：must多表示主观上认为必须干某事，而have to多表示客观上不得不干某事。比如：
I must go and help the sick old man.
我必须去帮助那个患病的老人。
I'll have to get up early tomorrow morning because the train will leave at 7 a.m.
我明天早晨必须清早起床，因为火车早上7点开。
I must go over the test paper again to see if there are any mistakes.
我必须再检查一遍试卷，看看是否有错误。
The teacher said that there were many mistakes in my test paper, so I had to go over it again.
老师说我试卷中有许多错误，所以我只好检查一遍。
4. should/ought to表示应该
should/ought to表示"责任"，通常解释为"应该"。比如：
We should/ought to be strict with ourselves in our work.
我们在工作中应该严格要求自己。
Staff should/ought to clock in on arrival.
员工到达时应该打卡记时。
They should not/ought not to leave today's work until tomorrow.
他们不应该把今天的工作拖到明天去做。
You should/ought to take care of her.
你应该好好照顾她。
5. must/may/might表示推测语气
（1）may/might表示可能性，可解释为"或许"、"可能"。比如：
It may rain this afternoon.
今天下午可能下雨。
It may be to sell a film.
或许是营销一部影片。
The coat is too close to the fire. It might get burnt.
这件上衣离火炉太近，可能会烤焦。
（2）must表示"一定，必定"，用于肯定结构。比如：
This must be the book you want.
这一定是你要的那本书。
This must be the movie you want to watch.
这一定是你想要看的电影。
They young man look s like Jimmy. He must be Jimmy's brother.
那个年轻人看上去像杰米。他一定是杰米的兄弟。
6. shall的用法
（1）Shall I…?表示想做某事征求对方意见。比如：
Shall I see you off at the station?
我到车站送你好吗?
Shall I take down this pictures?
我取下这幅画好吗?
Shall I tell you a story?
要我给你讲个故事吗?
（2）Shall we…?表示提出建议。比如：
Shall we go together?
我们一起去好吗?
Shall we go there by taxi?
我们坐出租车去那儿好吗?
Shall we get the luggage down before it stops? 我们是不是应该在停车前把行李拿下来?
7. will的用法
（1）will表示说话人的意愿。比如：
All right, I will take you there in my car.
好吧，我用车送你去那儿。
Though the hotel is not good enough, he will stay there.
虽然旅馆不够好，但他愿意在那儿过夜。
She won't let her classmates know about her difficulty.
她不愿意让她的同学们知道她的困难。
（2）Will/Would you…?表示请求，询问对方的意愿，常用来向对方发出邀请。比如：
Will/Would you please sing us a song?
请给我们唱个歌好吗?
Would you like a cup of coffee?
想喝咖啡吗?
Would you like to join us for dinner?
你来和我们一起吃饭好吗?
Can/Could you…?也可以表示请求。比如：
Can/Could you tell me if there is a shopping centre near here?
请问这儿附近有购物中心吗?
Can/Could you tell us something about your trip to Germany?
请给我讲讲你去德国的旅行?
（3）Would you mind+v-ing…?也可以表示语气较婉转的请求。也可以用Do you mind if…?比如：
Would you mind our having a party in this room?
我们在这个房间进行聚会你介意吗?
Do you mind if I smoke here?
我在这儿抽烟你介意吗?
8. need的用法
（1）need用作情态动词时，多用于否定与疑问结构，一般不用于肯定句，表示"必须"、"必要"。尤其在用于第一人称疑问句时，问话人希望听到否定回答。比如：
——Need you leave now?
你现在一定要走吗?
——Yes, I must.
是的，我一定得走。
——Need we copy these words in our exercise books?
我们一定要把这些单词抄在练习本上吗?
——No, you needn't.
不必了。
You needn't telephone him again.
你不必再打电话给他。
（2）need用作一般实义动词，可以根据需要作动词变形，也可以后接to动词不定式。比如：
He needs money now.
他现在需要钱。
We need to clean the lecture hall.
我们必须把演讲厅打扫一下。
They didn't need to go to work that day.
那天他们不必上班。
Did he need to buy another digital camera then?
他当时有必要再买一台数码相机吗?
(3) had better的用法
had better+动词原形（最好），表示建议或者劝告，其简略式为'd better。比如：
You had/'d better take this advice. It is good for you.
你最好接受他的意见。这对你有好处。
They had/'d better check the car engine before they leave.
他们最好在动身前把汽车发动机检查一遍。
had better否定形式为had better not+动词原形 最好不…。比如：
You'd better not go out alone at night.
你晚上最好不要单独外出。
We'd better not walk on the grass.
我们最好不要践踏草地。
