could/was-were able to
When I was a child, I .... spend hours climbing trees, but i have trouble climbing stair!
Could
Jackson's very intelligent. He .... read by the time he was three.
was able to
I .... do anything last week! I had the flu.
could not or was not able to
I .... talk briefly with your college advisor. She was very nice.
was able to
We were late, but we .... catch the train . It was also late
were able to