They will never be able to appreciate your kindness.
I was sure you would be able to (could) translate that article after you had translated so many texts on physics.
You will be able to go to the country when you have passed your last exam.
We can (shall be able to) pass to the next exercise when we have done this one.
I shall be able to give you my book for a couple of days after I have read it.
He has been able to ski for ten years.
We knew that she had been able to swim since childhood.
You won’t be able to take part in this serious swimming competition until you have mastered good skills.
I had not been able to solve the problem before he explained it to me.