Obligation, prohibition and permission
Use must, have to, must not, do not have to and can to describe rules, necessity and permission.
Learning goal: Obligation, prohibition and permission
Distinguish something necessary, forbidden, optional or allowed.
In a nutshell
Use must, have to, must not, do not have to and can to describe rules, necessity and permission.
When do we use it?
Distinguish something necessary, forbidden, optional or allowed.
Pattern
Form
Must/have to = necessary; mustn’t = forbidden; don’t have to = not necessary; can = permitted.
- You must wear a helmet.
- You mustn't smoke.
- You don't have to come.
- You can leave early.
Examples
Key contrast
Read the whole context and identify the time, meaning, noun type or sentence structure before choosing.
Watch out
Common mistakes
You don't have to smoke here.→ You mustn't smoke here.You mustn't come if you're busy.→ You don't have to come if you're busy.
Key takeaway
Remember
Use must, have to, must not, do not have to and can to describe rules, necessity and permission.
Self-check
Quick check
- Find the grammar clue.
- Check the subject and verb form.
- Confirm that the answer fits both structure and meaning.
Put it into practice
Ready to test Obligation, prohibition and permission?
A short interactive practice session with instant feedback — about 10 questions calibrated to C1 Advanced.
Start practice