Common Mistakes : Could

modal verb

BAD: As I’ve already mentioned, I could learn a great deal during the two years I spent in England
GOOD: As I’ve already mentioned, I was able to learn a great deal during the two years I spent in England

.BAD: By reading quickly, I could finish the book before the library closed
.GOOD: By reading quickly, I managed to finish the book before the library closed

:When talking about a skill or general ability in the past, use could or be able to
.By the time she was four, she could/was able to swim the whole length of the pool

When talking about a single event in the past, we usually use be able to or manage – NOT could
.Luckily, we managed to get there before the shops closed
?Were you able to start the car