could S1 W1 / kəd ; strong kʊd / modal 动词 ( negative short form couldn’t )

1 past ability used as the past tense of ‘can’ to say what someone was able to do or was allowed to do in the past :

By the time she was eight, she could read Greek and Latin.

In those days you could buy a box of cigars for a dollar.

Could you hear what I was saying?

I couldn’t get tickets after all, they were sold out.

I knew I couldn’t afford the rent.

The teacher said we could all go home.

2 possibility

a) used to say that something is possible or might happen :

Most accidents in the home could be prevented.

It could be weeks before we get a reply.

If you’re not careful, you could get into even worse trouble.

A faulty connection could easily (= would be likely to ) cause a fire.

b) used to say that something was a possibility in the past, but did not actually happen :

Somebody could have been killed.

I could have warned you if I had known where you were.

He could have escaped, but he chose to stand and fight.

3 emphasizing your feelings spoken used to emphasize how happy, angry etc you are by saying how you want to express your feelings :

He irritates me so much I could scream.

I was so angry I could have killed her.

I was so relieved I could have kissed them all.

4 requesting spoken used to make a polite request :

Could you help me with these boxes?

Could I have a drink of water, please?

How about Sam? Could he come along too?

I wonder if I could just ask you to sign this.

5 suggesting used to suggest doing something :

You could ask your doctor for a check-up.

You could always try phoning her at the office.

Maybe we could get together sometime next week?

Couldn’t you get one of your friends to help you?

6 annoyance spoken used to show that you are annoyed about someone’s behaviour :

You could have told me you were going to be late (= you should have told me but you did not ) !

You could at least say that you’re sorry.

How could you be so stupid!

7 couldn’t be better/worse/more pleased etc used to emphasize how good, bad etc something is :

Their lifestyles couldn’t be more different.

‘How are things?’ ‘Fine! Couldn’t be better.’

Ordering online couldn’t be simpler.

8 I couldn’t British English spoken used to politely say that you do not want any more food or drink :

‘Would you like another piece of pie?’ ‘Oh, no thanks, I couldn’t.’

9 could do with something spoken to need or want something :

I could do with a hot drink.

→ could do worse (than) at worse 1 ( 5 ) , → couldn’t care less at care 2 ( 5 ) , → couldn’t agree more at agree ( 1 )