be able to 和 can的区别是什么?有哪些用法?当都表示能够时

can和be able to的区别 can和be able to 的区别 be able to和can的区别 be able to的用法be able to和can的区别和用法 can,could和be able to的区别 can 与be able to 的具体区别 和 用法 can 和 be able to 的区别在哪? can和be able to的区别?要例句哦`` be able to、can、could的区别 can与be able to的区别 be able to与can 的区别 be able to 与 can的区别 be able to ,can,may的区别 be able to 和will be able to 的区别 我不是要be able to和can的区别和用法,我是要be able to和are/is able to的区别和用法.是有一道题：Nowdays people can travel to many places by air.保持句意不变.我把can改成了be able to,但是答案是are able to.所以 can be able to可不可以用（或者说有没有这个词组）我的意思是can be able to有没有这个词组..如果有.和be able to 有什么区别? be able to 和 able to的区别 英语中,can和be able to有和区别?