Student or Learner
Is there any difference in meaning when we use?
1-My granny didn't speak French very well but she could/was able to communicate with our guests from France.
2-Tarek couldn't/wasn't able to use computers at all until he took up a computer course.
3-Captain Scott and his team could/was able to reach the Pole but they couldn't/wasn't able to come back.
4- Einstein couldn't/wasn't able to speak until he was four or five but he could/ was able to count very quickly.
*For general ability in the past we can use was able to though could is more common.
e.g. I could/was able to swim when I was five years old.
*For a specific event showing success after trying, we use was/were able to, managed to, succeeded in, but not could.
e.g. I was able to/managed to solve her problems for her.
I wouldn’t use could in sentence three.