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can and could
A
can + infinitive (can do / can play / can come etc.):
| I/we/you/they he/she/it |
can can't (can not) |
do play see come etc. |
| can | I/we/you/they he/she/it |
do? play? see? come? etc. |
B
I can do something = I know how to do it, or it is possible for me to do it:
- I can play the piano. My brother can play the piano too.
- Sarah can speak Italian, but she can't speak Spanish.
- Can you swim? Yes, but I'm not a very good swimmer.
- Can you change twenty pounds? I'm sorry, I can't.
- I'm having a party next week, but Paul and Rachel can't come.
C
For the past (yesterday / last week etc.), we use could /couldn't:
- When I was young, I could run very fast.
- Before Maria came to Britain, she couldn't understand much English. Now she can understand everything.
- I was tired last night, but I couldn't sleep.
- I had a party last week, but Paul and Rachel couldn't come.
D
Can you ...? Could you ...? Can I ...? Could I ...?
We use Can you ...? or Could you ...? when we ask people to do things:
- Can you open the door, please? or Could you open the door, please?
- Can you wait a moment, please? or Could you wait a moment, please?
We use Can I have ...? or Could I have ...? to ask for something:
- (in a shop) Can I have these postcards, please? or Could I have ...?
Can I ...? or Could I ...? = is it OK to do something?:
- Tom, can I borrow your umbrella? or Tom, could I borrow your umbrella?
- (on the phone) Hello, can I speak to Gary, please? or ... could I speak ...?