情态动词用法总结及例句（could与具有情态意义的半助动词be）

1、在表现在能力时，can和be able to二者可以通用，但can较为常用，下面我们就来说一说关于情态动词用法总结及例句?我们一起去了解并探讨一下这个问题吧!

情态动词用法总结及例句

1、在表现在能力时，can和be able to二者可以通用，但can较为常用

He can speak English very well.=He is able to speak English very well. 他英语讲得很好。

2、在表将来能力时，二者虽然可以替换使用，但一般情况，多用be able to表示将来能力

I can't go to London this year. I hope I shall be able to go there next year. 今年我不能去伦敦了。我希望明年能去。

3、在表示过去能力时，could和was/were able to 一般可以通用。但是could表示泛指过去的能力，而was/were able to 还表示某个特定的过去能力

When I was young I could/was able to climb any tree in the forest. 年轻时，森林里的树我都能爬上去。（泛指过去能力）

Altough the driver was badly hurt, he was able to explain what had happened. 尽管受了重伤，司机仍能解释发生的情况。（某一特定的过去能力）

但是在否定句中，couldn't 和was/were not able to都是可以互换的

Although he worked hard, he couldn't /was not able to pass the final examination. 虽然学习努力，期末考试他未能及格。

4、be able to 只表“能力” ；can 除表“能力”外，还可以表“可能性、允许、怀疑”等

Any man can make mistakes, but only an idiot persists in his error. 人人都可能犯错误，但只有白痴才知错不改。（可能性）

You can keep the book until next Sunday. 这本书你可以用到下星期天。（允许）

Can it be true? This can't be true. 这可能是真的吗？这不会是真的。（怀疑、猜测）

5、“can have 过去分词”用于疑问或否定句中时，表示对过去发生的情况的“怀疑、不肯定”；be able to 后只跟不定式一般式，不跟完成式，但可以用“to have been able to”表示完成式

He can't have taken the book home. 他不可能把书拿回了家。

Where can he have gone? 他会去哪儿呢？

I'm sorry I haven't been able to do more for you. 对不起，我为你做得太少了。

6、be able to 前面可以使用其他情态动词和副词，可以和其他系动词连用；can则不能

He may not be able to come. 他或许不能来。

You might be able to persuade him. 你也许能说服他。

You should be able to name seven different colours. 你应该会说出7种不同的颜色。

He seemed able to put complicated thought in simple words. 他似乎能用简单的语言把复杂的思想表达出来。

7、be able to 有非限定形式，can则没有

He seems to be able to give up his bad habits. 他似乎能改掉坏习惯。

I would like to be able to read, but I am too old to learn. 我很想能去读书，但是我太老了，不能学。

Nothing is a greater misfortune than not being able to bear misfortune. 经不起不幸是最大的不幸。

8、be able to 可以有现在、过去、将来、现在完成、过去完成、将来完成6种时态；can只有现在和过去两种时态

I haven't been able to get in touch with her. 我还未能和她取得联系。

They had not been able to finish the experiment until last Friday. 直到上星期五他们才完成了这个实验。

Lanny could run and was a good tennis player. 拉尼善跑，并且是一个优秀的网球运动员。

9、be able to 往往指经过一番努力才能做到某事；can则无此意

He tried hard and was able to swim across the river. 他费了很大劲才游过了河。

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