How to use Could (do) and could have (done)

Could (do) and could have (done)

We use could in a number of ways. Sometimes could is the past of can

Listen. I can hear something. (now)
I listened. I could hear something, (past)

But could is not only used in this way. We also use could to talk about possible actions now
or in the future (especially to make suggestions).

A  :  What shall we do this evening?
B  :  We could go to the cinema.
A  :  When you go to Paris next month,you could stay with Julia.
B  :  Yes, I suppose I could.

Can is also possible in these sentences (‘We can go to the cinema.’ etc.). With could, the suggestion is less sure.

We also use could (not can) for actions which are not realistic.

I’m so tired, I could sleep for a week, (not I can sleep for a week)

Compare can and could:

·         I can stay with Julia when I go to Paris, (realistic)

·         Maybe I could stay with Julia when I go to Paris. (possible, but less sure)

·         This is a wonderful place. 1 could stay here for ever. (unrealistic)

We also use could (not can) to say that something is possible now or in the future.

The meaning is similar to might or may:

·         The story could be true, but I don’t think it is. (not can be true)

·         I don’t know what time Liz is coming. She could get here at any time.

We use could have (done) to talk about the past. Compare:

·         I’m so tired, I could sleep for a week, (now)
I was so tired, I could have slept for a week, (past)

·        The situation is bad, but it could be worse, (now)
The situation was bad, but it could have been worse, (past)

Something could have happened = it was possible but did not happen:

·         Why did you stay at a hotel when you were in Paris? You could have stayed with Julia.
(you didn’t stay with her)

·         I didn’t know that you wanted to go to the concert. I could have got you a ticket.
(I didn’t get you a ticket)

·         Dave was lucky. He could have hurt himself when he fell, but he’s OK.

We use couldn’t to say that something would not be possible now:

·         I couldn’t live in a big city. I’d hate it. (= it wouldn’t be possible for me)

·         Everything is fine right now. Things couldn’t be better.

For the past we use couldn’t have (done):

·         We had a really good holiday. It couldn’t have been better.

·         The trip was cancelled last week. Paul couldn’t have gone anyway because he was ill.
(= it would not have been possible for him to go)

o   Couldn’t have (done)

o   Could and might

o   Could l/you

o   Could with if 

o   Modal verbs