e able to 与can用法与区别
(1) be able to 强调努力而的能力,而can则强调自身已的能力.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 强调结果,而can只强调.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 可以有时态；而can现在和两种时态.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(from www.***.com).
(4) can可用于表示性,推测,允许等情况,而be able to通常不