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情态动词can与could的用法归纳

2016-12-24来源:和谐英语

情态动词cancould的用法归纳

1. 表示能力

(1) 表示现在的能力,用can,如:

He can (=He is able to) swim. 他会游泳。

He can speak English well. 他英语能说得很好。

I can’t remember where I put it. 我记不得把它放在那儿了。

(2) 表示将来的能力,通常用will / shall be able to,如:

I shall be able to come tomorrow. 明天我能来。

One day people will be able to go to the moon on holiday. 总有一天人们可以到月球上去度假。

但是,若表示现在决定将来是否有能力做某事,则可用 can,如:

Can you come to the party tonight?你今晚能来参加我们的聚会吗?

(3) 表示过去的能力。

① 若泛指过去的能力,可用could,如:

I could run faster then. 我那时能跑得更快一些。

②若表示过去特定场合做某事的能力,则不能用could,而用was / were able to do sth.,或用 managed to do sth,或用 succeeded in doing sth 等。如:

He studied hard and was able to pass the exam. 他学习很努力,所以考试能及格。

= He studied hard and managed to pass the exam.

= He studied hard and succeeded in passing the exam.

误:She could jump into the sea before the ship was blown up. 船爆炸之前,她跳进了大海。

正:She was able to jump into the sea before the ship was blown up.

注:在下列情况,could也可表示过去特定的能力:

①在否定句中,could和was / were able to可通用。如:

I couldn’t / wasn’t able to see him before he left. 他离开之前我没有再见到他。

②could与see, hear, smell, taste, feel, understand等表示感知的动词连用时。如:

I can hear you easily from here. 我在这儿就能很轻易地听到你的话。

Then he spoke slowly, but I could not understand him. 接着他说得慢了,但是我听不懂他的话。

③could用在间接引语中时。如:

He said he could finish the work next week. 他说他下周能完成工作。

顺便说一下,be able to还可用于完成时, 如:

I’m sorry I haven’t been able to come earlier. 对不起,我没有能够来得更早一些。

He said he had not been able to answer your letter. 他说他一直没能给你回信。

2. 表示许可

(1) 对于现在或将来的许可,用can或could均可,但could 语气更委婉, 如:

Can / Could I smoke in here? 我可以在这儿吸烟吗?

You can't pick the ball up in football. 踢足球时不许可用手持球。

I could come tomorrow if you like. 如果你愿意,明天我可以来。

② 表示自己允许别人做某事时, 答语应用can或may,而不用 could。如:

--Could / Can I use your pen? 我可以借用你的钢笔吗?

误:-- Yes, of course you could. 当然可以。

正:--Yes, of course you can / may.

(2) 对于过去的许可。 若表示过去一般性允许用could;表示过去特定的允许,则不用 could,而需换成其它表达,如had permission, was / were allowed to。如:

When I lived at home, I could watch TV whenever I wanted to. 我住在家里时, 想什么时候看电视就什么时候看。(一般性允许)

I was allowed to see the film yesterday evening. 昨天晚上允许我去看了电影。(特定的允许)

 

 

 

3. 表示推测

(1) 用can或could+动词的一般式,表示对现在或将来的推测。

①can通常用于否定句或疑问句中,而could则可用于肯定句、否定句或疑问句。如:

Even experienced teachers can make mistakes. 即使是有经验的教师也可能出错。

The wheel of history can not be turned back.历史的车轮决不会倒转。

I could go Beijing this summer. 今年夏天我们可能要去北京。(将来可能性)

You could be right, but I don’t think so. 你可能是对的,但我认为不是。(现在可能性)

(2) 用can / could +动词的进行式,对正在发生的情况进行推测。如:

What can / could he be doing at home now? 他现在在家可能在干什么呢?

He can’t be watching TV all day. 它不可能一整天都在看电视。

(3) 用can / could +动词的完成式。表示对过去的推测。如:

Alice can’t have written an article like that. Alice不可能写出那样的文章。

He can’t / couldn’t have arrived already. 他不可能已经到那儿。

He could have left. 他可能已离开了。

Where can / could he have gone? 他能到那儿去了呢?

还可表示“本来能够干某事”但事实并非如此,如:

He could have passed the driving test. 他本来能够通过驾驶考试的。(但事实没有通过)

You can / could have done it better. 你本来应该做得更好。

4. can还可表示惊讶,怀疑,不相信的态度

主要用于否定句、疑问句或惊叹句中,如:

Can this be true? 可能是真的吗?

How can you be so careless!你怎能如此粗心!

This cannot be done by him. 这不可能是他做的。

5. 常见的固定搭配

(1)can not help doing= can not but do 意为“不能不,禁不住”。如:

I cannot help laughing. = I cannot but laugh. 我不禁笑了出来。

I can’t help being what he be. 他成为这样的人物身不由己。

(2) cannot do / be too… 为“无论……也不过分”。如:

You cannot attach too much important to this matter. 你应该把这件事视为万分重要。

We can’t b too careful in driving a car. 我们无论如何谨慎驾驶也不过分。

We can’t praise him too much. 我们无论怎样表扬他都不过分。

(3) as… as one can / could 意为“尽可能地”,如:

I will come as soon as I can. 我尽可能早来。

I ran as fast as I could. 我尽快地跑。