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be able to与can的区别

时间:2015-08-21 09:19点击:

1、 be able to 强调通过努力而获得的能力,而can则强调自身已具有的能力.如:

She can sing the song in English.她能用英语唱这首歌.
He will be able to sing this song in English in a few minutes,too.几小时之后,他也能用英语唱这首歌.

2、 be able to 强调一种结果,而can只强调一种可能.如:

Luckily,he was able to escape from the big fire in the end.幸运的是,他终于逃出了大火.
If he got here a few hours earlier,I could save him.要是他早几小时来,我还能救他.

3、 be able to 可以有各种时态;而can只有一般现在和一般过去两种时态.如:

I could help you last night,but you didn't come.昨天晚上我能帮你,而你又没来.
Can you see it there?你能看见它在那儿吗?
He is / was / will be able to help you.他能帮你的忙
Will you be able to camera the lecture tomorrow?你明天能把讲座录下来吗?
I'm sorry I haven't been able to answer your letter in time.真对不起我没能及时给你回信.
Ps:指过去某时或某个时刻设法做成某事,不用could,而用was\were able to.
I talked with her for a long time,and eventually I was able to make her believe me.我谈了很久,最终还是使她相信了我的话.

4、 can可用于表示可能性,推测,允许等情况,而be able to通常不这样用.

You are able to use my pen.(误)
You can use my pen.(正)

5、 can有被动语态,主语为人或物皆可,而be able to只接不定式的主动形式,不接表示被动的不定式,也不可用无生命的名词作主语.例如:

The work is able to be done by him.(误)
He is able to do the work.(正)