Subject+to be(am is are)+Able to+Verb+Object

He is able to drive a car.
They are able to climb high mountains.
I am able to play the piano
You are able to swim.
Dogs are not able to climb trees.
Are you able to reach that high shelf?

We should use able to with differet tenses and modals

I was able to use a computer when I was 8.
He was able to read at the age of 6.
He should be able to start his own company now.