Modal Verbs, Can and Could in English

Modal Verbs, Can and Could in English

CAN

ABILITY
(Present)
can speak five languages.
POSSIBILITY
(Present)
Alcohol can cause cancer.
PERMISSION
(Informal)
Can I use your computer, please?
REQUEST
(Informal)
Can you hand me the pen?
OFFER
(Help)
If they like, I can carry some bags for you.

COULD

ABILITY
(Past)
He could play football well when he was a kid.
POSSIBILITY
(Past)
A lot of crime could be prevented.
PERMISSION
(Polite)
Could I please use your computer?
REQUEST
(Polite)
Could you tell me where the post office is, please?
SUGGESTIONIf you want, we could go out for dinner after school?