English Grammar for proficiency: Modal verb 'could'.

Could is used as the past tense of 'can' to talk about a past competence or a current possibility, request, permission, and suggestion.

Structure
Affirmative (subject + could + V1)
• I could run fast.
Negative (subject + could + not + V1)
• I couldn't run fast.   • I could not run fast.
Question (could + subject + V1)
• Could you run fast?

Usage

Past ability
It is used as the past tense of can, to talk about a person's past ability or skill.

• He could swim very well.

• I knew that you could do that.

• When I was younger I could run fast.

• He couldn't come to the party yesterday.

Permission
It is used to politely ask permission to do something.

• Could I borrow your umbrella?

• Could I use your phone, please?

Request
It is used to politely ask someone to do something.

• Could you open the door?

• Could you pass me the salt?

Probability
It is used to indicate that something is possible.

• He could be right.

• He could have lost his job.

• The accident could be prevented.

Suggestion
It is used to make a suggestion.

• We could eat out tonight, if you like.

• I wonder if we could go to the beach this weekend.

Annoyance
It is often used to indicate disturbance or annoyance in an angry way.

• I'm so pissed off I could scream!

• You could have told me the truth!

☞ When 'could' is used to make requests or ask permission to do something, the question is answered with 'can'. • “Could I ask a question?” “Yes, you can.” • “Could I borrow your book, please?” “No, you can't.

Example Sentences with 'Could'

• I could play the piano then.

• He said that he couldn't come to the party.

• She could read French when she was four

• I couldn't believe my eyes when I saw her.

• Could you repeat that, please?

• I couldn't sleep last night because of the noise.

• We could be making a big mistake.

• The situation couldn't be worse!

• You could at least try to help me!

• He asked if we could meet at the library.

• I wasn't sure if I could do that.

• I'm not sure if I could do that.

• I'm not sure if I could have done that.

• If I had time, I could help you with your project.

• I wish I could turn back time and make different decisions.

• If you could lend me some money, I would really appreciate it.

• I wonder if we could meet at the park instead of the coffee shop.