Can / Could


Can and Could ,are used mainly to express – ‘ABILITY.

EXAMPLES

Can – is present tense.

I  can run  for 10 miles in a go.

Could – is past tense.

I  could run  for 10 miles in a go, when I was 25.



Could , is sometimes used to express – ‘POSSIBILITY‘.

EXAMPLES

I  could win  this competition.

– This means that it is possible for me to win this competition.

He  could have managed  this situation in a better way.

– This means that it was possible for him to manage this situation in a better way.



Can and Could , are also used to express – ‘PERMISSION.

EXAMPLES

Can I  leave now?  –  This sounds less formal.

Could I  leave now?  –  This sounds more formal.



Can and Could ,are also used to express – ‘REQUEST.

EXAMPLES

Can you please  give me a glass of water?  –  This sounds less formal.

Could you please  give me a glass of water?  –  This sounds more formal.