The rule, as people use it

These five follow the same shape as will and should. The verb after them stays plain: "She can swim", never "She cans swim" or "She can to swim". Each one answers a different question.

"Can" is ability and permission in the present: "I can drive." "Can I sit here?" "Could" is its past ("I could read when I was four") and also the polite way to ask: "Could you help me for a second?" Asking with "could" instead of "can" is one of the fastest ways to sound polite.

"May" and "might" are both about possibility, and in conversation they mean almost the same thing: "It might rain later." "I may be late." "Might" is more common in everyday American speech. "May" also asks permission, formally: "May I come in?" You'll hear it in offices, hotels and restaurants more than between friends.

"Must" is strong. It's for rules ("You must wear a helmet") and for a confident guess ("You must be tired after that flight"). For everyday obligation, most speakers prefer "have to": "I have to leave at five." And watch the negatives. "You mustn't park here" means it's forbidden. "You don't have to come" means it's your choice. Mixing these two up changes the whole message.

Examples

Tap a sentence to hear it. Say it after the voice.

Fill the gap

Type the missing words, then check. The full sentence plays when you get it.

  1. 1

    (can / could) you pass me the salt, please?

  2. 2

    When I was a kid, I (can) run really fast.

  3. 3

    Take an umbrella. It (might) rain later.

  4. 4

    Haruto (can / not) come tonight, he's working.

  5. 5

    You've been traveling all day. You (must) be tired.

  6. 6

    You (must not / don't have to) smoke in the building.

  7. 7

    It's Saturday, so I (must not / don't have to) set an alarm.

  8. 8

    (may / might) I ask you a quick question?

Practice · 3 min

Write two sentences for each: something you can do, something you could do as a child but can't now, something that might happen this week, something you have to do tomorrow, and something you don't have to do this weekend. Then write one polite request with "could you". Say all eleven out loud, and check that "don't have to" and "must not" are used for the right meaning.

Say it today

Use it once in a real conversation before tomorrow. Out loud counts, even to yourself.