be able to的用法讲解和造句如下：

1.be able to翻译
表示“能够做某事”，强调通过努力而获得的能力。
She is able to play the piano.
她能够弹钢琴。
I am able to drive the truck.
我能够开那辆卡车。
She is able to speak three languages.
她能够讲三种语言。

2.be able to后面接动词原形
be able to do sth. 能够做某事

[造句]：
He is able to drive a car.
他会开车。
They are able to sing the song.
他们能够唱这首歌。

3.be able to的时态
一般现在时：am/is/are able to
一般过去时：was/were able to
一般将来时：will be able to
现在完成时：have/has been able to
[造句]：
I am able to run very fast.
我能够跑得非常快。
He was able to make lots of friends when he was young.
当他年轻的时候，他能够交很多朋友。
They will be able to finish the work soon.
他们很快就能够完成工作。
I wonder whether they have been able to find jobs.
我想知道他们是否（已）能够找到工作。

4.be able to的否定
一般现在时：am not/isn’t/aren’t able to
 一般过去时：wasn’t/weren’t able to
一般将来时：won’t be able to
现在完成时：haven’t /hasn’t been able to

5.be able to的同义词
was/were able to ≈ could
am/is/are able to ≈ can

wasn’t/ weren’t able to ≈ couldn’t （最常用）
am not/ isn’t /aren’t able to ≈can’t

be able to的否定式与be unable to同义
比如：
isn't able to = is unable to
weren’t able to = were unable to

以上就是be able to的用法讲解和造句。经常涉及到的知识点链接：
be able to 和can的区别