表推测的情态动词用法小结

英语中有不少情态动词都可以表示推测，其语气有强有弱，表示的可能性有大有小，现将它们的用法归纳如下：

1. 接近100%的可能

这当然只有must才具有这么高的可能性，它的意思是“一定”“肯定”，所作出的推测几乎接近事实。如：

That hat must be Tom’s. 那帽子一定是汤姆的。

He must be coming by bus. 他一定是乘公共汽车来。

2. 很有可能

表示可能性较大的情态动词主要有may, should, ought to，它们大致相当于汉语的“可能”“应该”“按理会”。如：

She should [ought to] be here soon. 她应该很快就到。

We may be buying a new house. 我们可能要买一座新房子。

3. 一般性的可能

在所有表示推测的情态动词中，might和could所表示的可能性最小，由于它们的语气较委婉，较不确定，所以往往相当于汉语的“可能”“也许”“说不定”等。如：

He might be waiting for you. 他可能在等你。

She might not like the idea. 她或许会不赞成这个想法。

We could all be millionaires one day. 我们有一天可能都成为百万富翁。

4. 理论上的可能性

表示理论上的可能通常是用can，且可以用于肯定句中。如：

Food poisoning can cause death. 食物中毒可导致死亡。

This kind of thing can happen every now and then. 这种事情是随时可能发生的。

New England can be very hot in September. 新英格兰有时9月份很热。

所谓理论上的可能性，就是指仅从理论上去考虑其可能性，至于实际情况如何，则不作考虑，比如说“食物中毒可导致死亡”，这只是理论上的一种推断，至于某人某次食物中毒了，他是否会死亡，则不在考虑之列，所以说，这种推测是非常“宏观”的！

5. 表示对过去情况作推测

如果表示对已经发生的情况作推测，不能用“情态动词+动词原形”，也不能用“情态动词的过去式+动词原形”，而是要使用“情态动词+动词完成式”。如：

He could have gone off with some friends. 他可能跟几个朋友出去了。

Mathews may have written that letter. 这封信可能是麦修斯写的。

I must have mistaken what you meant. 我一定误会了你的意思。

【跟踪训练】

1. We ________ a worse day for the picnic — it rained nonstop.

A. couldn’t pick                                   B. couldn’t have picked

C. might not pick                                 D. might not have picked

2. If you’re not careful, you ________ get into even worse trouble.

A. need                                               B. can

C. could                                              D. must

3. Don’t worry—they ________ to phone.

A. can just forget                                 B. could just forget

C. can have just forgotten                     D. could have just forgotten

4. Somebody ________ the cage—the lion ________ on its own.

A. must open, couldn’t escape               B. must open, couldn’t have escaped

C. must have opened, couldn’t escape    D. must have opened, couldn’t have escaped

5. That car nearly hit me; I ________.

A. might be killed                                 B. might have been killed

C. may be killed                                   D. may have been killed

6. “________ I sign this?” “No, there’s no need.”

A. Can                                                B. May     

C. Must                                              D. Might

7. Their answers are exactly the same — one of them ________ from the other.

A. must copy                                      B. must have copied

C. could copy                                     D. should have copied

8. It is usually warm in my hometown in March, but it ________ be rather cold sometimes.

A. must                                              B. can                     

C. should                                            D. would

9. Liza ________ well not want to go on the trip—she hates traveling.

A. will                                                B. can                     

C. must                                              D. may

10. Thank you for all your hard work last week. I don’t think we ________ it without you.

A. can manage                                    B. could have managed

C. could manage                                 D. can have managed

11. Although this ________ sound like a simple task, great care is needed.

A. must                                              B. may                    

C. shall                                               D. should

12. You ________ be hungry already—you had lunch only two hours ago!

A. wouldn’t                                         B. can’t                   

C. mustn’t                                           D. needn’t