原标题：大学英语常识点：can、may、must表估测的用法

1、can/may/must表估测的用法

can, may, must等都可用于表估测，但它们的意义和用法不一样。

must口气最必定，指“必定、必定”，只用于必定句中。“must+动词原形”标明对如今情况的估测；“must + have + done ”标明对曩昔情况的估测。如：

Mum must be cooking supper now.母亲如今必定在做晚饭。

He must have finished his work.他必定结束他的作业了。

May/might 标明“或许，可以”。如：

Tom may go abroad next year.汤姆下一年可以要出国。

She might have finished the work.她可以已结束这项作业了。

He can’t know the answer.他不可以能晓得这个答案。

can/could 标明“可以，会”，我用于否定和疑问句中。如：

Could she he at home?她可以在家吗？

can,标明一时的情况，意为“有时侯会……”。

can的这种用法，只用在必定句中

。如：

Children are lovely, but they can be tiring.

Training by yourself in a game can be highly dangerous.

2、case 用法小结

(1)名词case的词意

①意为“景象、情况”。

If that’s the case, you’ll have to work much harder.假定是那种景象的话，你将不得不愈加尽力地作业。

②意为“病例、事例”。

There were seven cases of cholera.有7起霍乱的病例。

The civil case will be heard in court next week. 这一案子将于下星期审理。

③意为“箱、盒、容器”。

John bought a case of beer.约翰买了一箱啤酒。

(2)由case构成的短语

①in case 意为“因为可以发生某事、以防如果”，是介词短语，在句中作状语，常可置于句尾；也可用做连词，后跟that从句(that常省掉)，标明条件或意图，从句谓语习气用should+动词原形(should常省掉)或陈述口气。

It may rain—you’d better take an umbrella(just)in case(it does).可以下雨——你最佳带把雨伞，以防如果。

In case(=If)he arrives before I get back, please ask him to wait.假定他在我回来之前到，请让他等一下。

He doesn’t dare to leave the house in case(that)he should be recognized.他不敢出门，生怕被认出来。

②in that case 意为“已然那样、假定果那样的话”，用来承受上文。

In that case, you wouldn’t have a pan on fire. You’d have a house on fire！要是那样，你就不但使锅着火，你还会把房子烧起来。

You don’t like the job? In that case why don’t you leave?你不喜爱这份作业？那你怎么不辞掉呢？

He may be late. In that case we ought to wait for him.他可以迟到，因而咱们大约等他。

③in any case 意为“不管如何、总之”。

We have to help him to pay the debt in case.咱们不管如何要帮他还账。

④in no case 意为“在任何景象下决不、不管如何都不”，用于句首时语句要进行有些倒装。

In no case shall I forget the expression on her face.我决不会忘掉她脸上的表情。

⑤in case of sth. 意为“若发生某事、假定、假定”，是短语介词，后接名词、代词、-ing方法作宾语。

In case of fire, ring the alarm bell.遇火灾时当即按警铃。

In case of rain（=In case it rains）,they can’t go.要是下雨，他们就走不了了。

In case of his being absent, we’ll put off the meeting till next week.假定他缺席，咱们就会把会议推迟到下周。

⑥in the case of 意为“至于、就……来说”，是短语介词。

In the case of your debt, I’ll pay it off for you.至于你的欠款，我会替你还清的。

3、catch fire/ on fire

catch fire 意为“着火”，标明动作。on fire 意为“着火、在燃烧”，标明状况。如：

Suddenly a pan of oil catches fire.

Soon the whole floor was on fire and it was impossible for people on the floors above to escape.回来搜狐，查看更多

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