情态动词用法点拨

情态动词,顾名思义是用来表示说话人的语气、态度和情感的动词。情态动词一般没有人称和数的变化,不能单独作谓语,必须和动词原形一起使用。虽然情态动词数量不多,但是各自表达的意思却很丰富,如果不进行归类,容易混淆。下面是小编整理的一些关于情态动词用法分析，以供大家学习参考。

can,could和be able to可用来表示能力。be able to可用于各种时态,且was / were able to表示“成功做了某事”。例如:

Though the earthquake hit the village, all the villagers ______ move to the safe areas.

A. would B. could

C. were able to D. need

分析 C 尽管地震袭击这个村庄,村上的人成功地撤到了安全地带。were able to表示“成功做了某事”。

　　can和could表示有能力,但不一定做到。例如:

He could be in time for the first class this morning, but there was a traffic accident. 他本可准时到校上第一节课,但路上发生了交通事故。

can和may可用来表示“允许”或者征求对方的意见(请注意在疑问句和答句中的用法):

—Could I visit you again next Christmas?我能在明年圣诞节再来拜访您吗?(语气委婉)

—Yes, you can. / No, I’m afraid not. 好啊。/ 恐怕不行。

—May I watch TV after finishing my homework? 做完作业可以看电视吗?

—Yes, you may. / No, you mustn’t. / No, you’d better not. 可以。/ 不行!/ 最好别看。

will / would在疑问句中用于第二人称时,表示询问对方的意愿或向对方提出请求,后者更为婉转:

Will / Would you get me some souvenirs when you visit Shanghai Expo?你可以在参观上海世博会的时候给我带些纪念品吗?

　　在疑问句中,shall 用来征求对方的意见或者请求指示:

Shall I fetch some orange juice for you? 要不要我给你拿些橘子汁来?

Since everybody is here, shall we start the meeting now? 既然每个人都到了,我们开会吧?

There’s an applicant for the interview. Shall he come in right now? 有位来应聘的。要不要他马上进来?

　　must表示“必须,应该”,是说话人的主观意愿;否定式mustn’t表示“不应该,不准,禁止”等:

We must observe the traffic rules. 我们必须遵守交通规则。

You mustn’t farm on the Internet as a student, which costs lots of time. 作为学生不能网上种菜,那很耗时间的。

have (has) to表示客观上的“需要,不得不”,强调来自外界的义务:

It is time for the PE lesson. I have to go now. 是体育课的时间了,我得走了。

He is old enough now. You don’t have to worry about him. 他年龄不小了,你不必为他担心。

　　shall用于第二、三人称,表示说话人的命令、警告、威胁、强制等意思:

If you didn’t do as I told you. You shall not watch TV this evening. 你没按照我说的去做,所以你今晚不能看电视。

No one shall smoke in this area. 任何人都不可以在这个地方吸烟。

　　should 表示职责、义务、劝告等,主观性强:

You shouldn’t judge a man always by his appearance. 你不应该总是以貌取人。

should和ought to的含义大致相同,ought to 强调义务或责任时,比should语气强:

You ought to go and see Mary tomorrow. 明天你应该去看玛丽。

　　will和would表示决心、意志、意愿等,用于各种人称:

I will make the computer work even if I have to stay up all night. 哪怕我熬夜也要修好电脑。

She will help you if you can’t finish cleaning the classroom before 5:00. 如果你在5:00前不能完成打扫教室的任务,她会帮助你的。

表示推测的情态动词有must, can, could, may, might, should等。must表示推测时,意思是“一定、准会”,语气肯定,有把握,只能用于肯定的猜测,可以推测现在正在发生的动作和过去发生的动作。can和could表示推测时,往往用于否定句或疑问句,can’t表示“一定不”。

may, might表示推测时,意思是“可能、也许”,语气没有must肯定。may, might表推测时,还可以用于否定句,意思是“可能不、也许不”,但不用于疑问句。might不表示过去时态,只是语气上比may更委婉,表示可能性更小。should表示推测时,其语气比较肯定,并暗示其推测有一定的事实依据或者合乎客观常理。例如:

This book should be found easily in the library. 在图书馆应该很容易找到这本书的。(说话人认为,图书馆应该有很多这类书籍,所以应该很容易找到。)

He must have enjoyed the film Avatar, otherwise, he wouldn’t want to see it a second time. 他一定很喜欢电影《阿凡达》,否则他就不会再想看第二遍了。

—Someone called you while you were away, but he didn’t say who he was. 你不在时有人打你电话了,但他没说他是谁。

—Thanks. Who can it be?谢谢!他会是谁呢?

Look at that car! It must be driving at least 150 kilometers an hour. 看那车开得多快!起码每小时150公里。(must be driving表示对现在正在发生的事情的肯定猜测)

There is no one in the classroom. All the students must have gone to the Charity Bazaar. 教室里没有一个人,学生一定都去Charity Bazaar了。(must have gone表示对过去事情的肯定猜测) could have done / might have done“本来能够做而实际上没有做”,用来表示对过去没有做成某事的遗憾或责备;should have done / ought to have done“本应该做某事而实际上没有做”,用来表示责备或后悔;shouldn’t have done / ought not to have done“本不应该做某事但却做了”,用来表示责备或后悔;needn’t have done“本来不必做却做了某事”。例如:

You should / ought to have come to the meeting earlier. 你应该早点来开会。

He shouldn’t / ought not to have treated his parents like that. 他不应该那样对待自己的父母。

As you worked late yesterday, you needn’t have come this morning. 因为你昨晚熬夜工作,没有必要今天上午来的。

—I stayed at a hotel while in London. 在伦敦期间我住在旅馆。

—Oh, why not contact Grace? You could have stayed at her home. 哦,你为何不联系格雷西?你本来能住她家的呀!

　　should意为“竟然”,表示惊奇、遗憾:

I’m surprised that you should be late today. 我很惊讶你今天竟然会迟到。

　　need表示“需要,必须”,多用于疑问句和否定句中:

—Need we buy a laptop?我们有必要买笔记本电脑吗?

—No, we needn’t. / Yes, we must. 没有必要。/ 有必要。

　　dare表示“敢”,多用在疑问句和否定句中:

Dare you swim across the river?你敢游到河对面去吗?

She dare not speak in public. 她不敢在公共场所说话。

　　need和dare作为行为动词时,其变化与一般动词相同。作实义动词的dare在否定句中其后的to可以省略:

We need to think it over. 我们需要仔细思考。

She didn’t need to do such a part-time job to cover her tuition expense. 她没必要打工去挣学费。

—Who dares to go? 谁敢去?

—I don’t dare (to) ask her. 我不敢去问她。