could */*/*/

weak [kəd] , strong [kʊd]

modal verb summary: ■ Could is used as the past tense of can when it means that someone had the ability to do something, or that something was possible: The Roman army could march 30 miles in a day. ■ Could is usually followed by an infinitive without ‘to': I'm glad you could come. Sometimes it is used without a following infinitive: I came as quickly as I could. ■ Could has no tenses, no participles, and no infinitive form. It does not change its form, so the third person singular form does not end in ‘-s': She could play the violin when she was six. ■ Questions and negatives are formed without ‘do': Could he help you? ♦ I could not breathe. ■ The negative form could not is often shortened in conversation or informal writing to couldn't: I couldn't find her phone number.

1) past tense of ‘can' used for saying that someone was able to do something

Renee could read when she was four.[/ex]

In the distance I could see a cloud of smoke.[/ex]

2) for saying what is possible used for saying that something is possible or that it may happen

We could still win.[/ex]

In a situation like this, anything could happen.[/ex]

3) in requests spoken

used for asking something politely

Could I have a glass of water?[/ex]

Could you post this letter for me?[/ex]

I wonder if we could borrow your car?[/ex]

See:

can I

4) for making a suggestion spoken

used for suggesting to someone what they might do

You could come and stay with us.[/ex]

You could always sell the car if you need extra money.[/ex]

5) for emphasis spoken

used for emphasizing how strong your feelings are

How could you be so stupid![/ex]

•

could have — spoken 1) used for saying that something was possible in the past, even though it did not happen[/ex]

You could have been killed.[/ex]

She could have married Gerald if she'd wanted to.[/ex]

— 2) used for saying that perhaps something was true, although you are not sure

The explosion could have been caused by a gas leak.[/ex]

couldn't be better/worse/nicer etc — spoken used for emphasizing that someone or something is extremely good/bad/nice etc[/ex]

I was so nervous, but she couldn't have been nicer to me.[/ex]