Must, have to and should
Use must and have to for strong obligation, mustn't for things that are not allowed, don't have to when something is not necessary, and should for advice.
How it works
- Have to: rules and obligations from outside. I have to wear a uniform.
- Must: strong obligation, often the speaker's own feeling or a written rule. I must call my mum. Passengers must wear seat belts.
- Mustn't = it is not allowed. Don't have to = it is not necessary, you can choose.
- Should / shouldn't: advice or what is right. Ought to means the same and is less common.
- Must has no past form: use had to. I had to work late yesterday.
- Modals take the base verb without to: must go, should go (but have to go, ought to go).
Examples
You mustn't smoke inside the building.
You don't have to bring your laptop. We'll provide one.
I have to be at the office by 8:30 every day.
You should try the bun cha near the station.
We had to wait two hours because the flight was delayed.
Common mistakes
Wrong: You
mustn'tcome to the party if you're busy.Right: You don't have to come to the party if you're busy.
Wrong: I must
tofinish this report today.Right: I must finish this report today.
Wrong: Yesterday I
muststay late at work.Right: Yesterday I had to stay late at work.
Practice
1 of 14Fill the gap.
Level: EGP Modality (obligation and necessity): must and have to are A2; mustn't vs don't have to, should for advice and had to for past obligation are B1 points. Written for Gloss.