can and could

Can:

The use of can is as follows.

a.       General Possibilities

1.      You can ski on the hills. There is enough snow.

2.      We cannot bath here on account of sharks.

3.      Can you get to the top of that mountain in one day?

You might have notices that possibility, impossibility shown in the above sentences is not meant only for one person but for general public.

The factors making possible or impossible are external.

b.      Ability

1.      She can speak English.

2.      Fish cannot swim out of water.

3.      He can help you.

The ability or otherwise depends upon the individual. The individual is capable or not capable of doing something.

3. Permission

1.      Can I borrow your car? Of course, you can, cannot.

4. For orders

1.      This is an awful word. You cannot do it again.

2.      You cannot go there again.

3.      You cannot leave office early.

5. Offer

1.      Can I help you?

2.      I can give you this pen if you hurry.

6. Opportunity

1.      You can catch the 7:30 train if you hurry.

Could:

1. It shows permission in past

I could use my father’s car whenever I liked.

2. Express ability in past

i.                    She could speak English when she was six.

ii.                  They could not find the way home that night.

It may be noted that “could” is the past tense of “can” and we have seen in the above sentences that it has been used for past time, but now let us see how we can use it for other times.

i.                    Could I borrow your car next week? It shows permission, asking for permission for future.

ii.                  Could you hold the door open for me? It is request for present time.

iii.                You could type this for me now or tomorrow. It is an order for present time or future.

iv.                Come early so we could have a picnic. It is a suggestion for present or future.