Intermediate Grammar
Master English grammar one unit at a time. Clear notes, then 40+ interactive exercises with instant feedback — based on the topics in English Grammar in Use (Intermediate).
Have to and must“have to · must · mustn’t · don’t have to” — 44 interactive questions
📖 Grammar Reference — Have to and must
Study the notes, then work through the six exercises.
A have to — external obligation
Use have to when the obligation comes from outside — a rule, a law, a boss, a schedule, or circumstances. The speaker is not personally imposing the rule.
| rule / law | All drivers have to wear a seatbelt — it’s the law. |
| circumstance | The lift is broken, so we have to take the stairs. |
| job requirement | She has to attend the weekly team meeting. |
B must — personal obligation / strong recommendation
Use must when you feel the obligation — a personal decision, a strong recommendation, or an inner voice. It expresses the speaker’s own authority or strong feeling.
💡 In everyday speech, have to and must are often interchangeable for obligation — but must sounds more personal or urgent.
C mustn’t vs don’t have to
These two look similar but mean very different things:
| mustn’t | Prohibition — it is not allowed. | You mustn’t smoke here. (= it is forbidden) |
| don’t have to | No obligation — it is not necessary, but you can if you want. | You don’t have to wear a tie. (= it’s optional) |
D Past & future forms
must has no past or future tense. Use have to for those forms:
| past | had to | We had to wait an hour — the train was delayed. |
| future | will have to | You will have to register online from next month. |
| after modal | have to | You might have to pay a deposit. · You should have to… ✗ |
| present perfect | have had to | She has had to cancel twice already. |
Made with care for English learners · allenglish4u.com
Original practice material inspired by the English Grammar in Use syllabus (Cambridge University Press). Example sentences and exercises are written by All English 4U.