Study materials
You are on a train and want to take the free seat next to a stranger. The same idea can be said in three ways, and each sounds different.
Can I sit here?
Casual.
Could I sit here?
Polite.
May I sit here?
Formal.
This article explains how to ask permission for yourself and a favour from someone else, how to answer a request, how may not works on signs, and how could expresses ability in the past. Could, may and might for guesses are explained in the previous topic.
Requests and permission
When you ask for permission, the words line up from the everyday to the formal.
| Form | Tone | Example |
|---|---|---|
| Can I | casual, among people you know | Can I sit here? |
| Could I | polite, fits almost anywhere | Could I sit here? |
| May I | formal and fairly official | May I sit here? |
May is used in requests only with I or we, to ask permission for yourself. To ask another person for a favour, say could you, or simply can you among people you know.
Could you repeat that, please?
Could you help me with this box?
An even more polite way to ask a favour is would you: Would you carry this bag for me? In a cafe or a shop you ask for a thing the same way: Can I have a cappuccino, please? or, more politely, Could I have the bill, please?
How to answer a request
People usually agree without a modal: Sure, Of course, Go ahead, No problem. If a modal is needed, permission is given with can or may: Yes, of course you can. Could in a request only makes it more polite, so the answer Yes, you could does not fit.
People refuse gently with I'm afraid not and briefly say why.
Could I borrow your drill? I'm afraid not. It's broken.
Bans with may not and can't
In official rules and on signs, may not means a ban. In conversation the same ban is can't.
Visitors may not enter.
On a sign.
Sorry, you can't park here.
In conversation.
Could as the past of can
Could is also the past of can in the sense of being able to.
I could swim when I was five.
She couldn't find the address.
The meaning is clear from the sentence. Past ability comes with a specific time, like when I was five, and a guess comes without one.
Could in a request and could for past ability differ in meaning. Could you turn the music down? asks for something now, and I could swim when I was five tells about the past.
Common mistakes
The first is asking another person for a favour with may.
May you help me? → Could you help me?
May asks permission only for yourself.
The second is putting do into the question.
Do you could open the door? → Could you open the door?
Could moves in front of the subject itself.
The third is using can for past ability.
When I was six, I can ride a bike. → When I was six, I could ride a bike.
The past of can is could.
The first mistake shows after may. It asks permission only for yourself, with I or we, and a favour is asked with could you or can you. The second shows at the start of the question. Can, could and may move in front of the subject themselves, so do is not needed. The third is caught by asking whether it is about the past. Then ability is could, not can.