We use 'could' to express different things:
- Making polite requests;
- Making suggestions;
- Expressing possibility;
- As the past form of can.
Making Polite Requests
We use 'could' in questions to make polite requests.
Could I borrow your pen, please?
I want to borrow your pen. I am asking you if it is ok.
We also use 'can' for requests, but 'could' generally sounds more polite.
We use 'could' to make suggestions. We often use 'could' for suggestions when we are exploring different options. It is not a strong suggestion.
We could go to the cinema tonight.
I'm suggesting we go to the the cinema.
I could meet you after work.
I'm suggesting that we meet after work.
We can use 'could' to talk about something that is possible, but that we are not certain of.
I could be late tonight. I have a lot of work to do.
It is possible that I will be late. I'm not sure.
The queue is very long. We could be waiting for hours.
It is possible that we will need to wait a long time. We don't know how long we will have to wait.
We can also use 'might' to express possibility. Learn more about using might.
We use the negative, 'could not', to say something is impossible.
Jane couldn't have stolen the money. She was away that day.
It was impossible for Jane to steal the money because she was away.
The short form of could not is couldn't. Learn more about short forms.
The Past Form of Can
We use 'could' as the past form of 'can' to talk about ability or possibility in the past.
I could touch my toes when I was younger.
I was able to touch my toes in the past (when I was young).
I couldn't complete the exam yesterday.
I was not able to complete the exam.
You could see the ocean from here before they built the city.
It was possible to see the ocean in the past (before they city was built).
Making Sentences Using Could
+ We could go to the cinema. s=we + could + v
- We couldn't go the the cinema. s=we + could + not + v
? Could we go to the cinema? could + s=we + v