Question

be able to和can的区别

Answer 1

can 和be able to 都可以表示能力.can泛指一般的能力,而且只有两种形式,即:can,could．be able to 则主要指具体做到了某件事的能力,其形式主要是靠be 发生变化,所以形式比can 多．可以说：I can swim.I am able to swim.但是不能说：All the people could escape from the big fire in time.只能说：All the people were able to escape from the fire in time.

Answer 2

can 与be able to在用法上既有相同的一方面, 又有不同的地方,这是应该引起注意的。当它们表示能力的时候，是同义的。如：
He can speak two foreign languages.
He is able to speak two foreign languages.
它们用法上的不同主要体现在以下几方面:
1. can只有两种时态, 即can 和could, 而be able to 有多种时态, 如was/were able to, will/shall be able to, have/has been able to等:
I’ll be able to drive the car in a week.
Through his diligent work, the deaf-mute has been able to read and write in a sign language.
2．表示过去通过努力终于做成了某事要用be able to，而不能用can。如：
I was able to swim to the bank after the boat turned over.
can 和be able to 都可以表示能力.can泛指一般的能力,而且只有两种形式,即:can, could．be able to 则主要指具体做到了某件事的能力，其形式主要是靠be 发生变化，所以形式比can 多．可以说：I can swim. I am able to swim. 但是不能说：All the people could escape from the big fire in time. 只能说：All the people were able to escape from the fire in time.
3．can能表猜测，be able to不能。can的这种用法主要用于疑问句和否定句。
Somebody is knocking at the door. Who can it be?
It can’t be our teacher who is knocking at the door.