Six rule forms, four meanings
Most school rules use six short forms. Learn them by meaning: “OK”, “Do it!”, “Don’t do it!” and “No need”.
- “can” (OK): “You can borrow three books.”
- “can’t” (not OK): “You can’t use your phone in lessons.”
- “must” (a rule): “You must be in class by 8.30.”
- “have to” / “has to” (necessary): “We have to wear trainers in the gym.”
- “mustn’t” (don’t do it): “You mustn’t run in the corridors.”
- “don’t have to” (not necessary): “You don’t have to buy lunch.”
Mustn’t or don’t have to: the difference that matters
In positive sentences, “must” and “have to” both mean something is necessary. In the negative, they split: “mustn’t” means it is against the rules; “don’t have to” means there is no rule, so you choose. Test: if you can add “but you can if you want”, use “don’t have to”.
- “You mustn’t eat in the lab. It isn’t safe.” → don’t do it.
- “You don’t have to wear a uniform.” → wear what you like.
- “It’s Saturday, so I don’t have to get up early.” → no need.
Listen: the rules at a new school
Three students check the signs at their school. One is new and remembers her old school in Accra, Ghana. Notice “had to”: “must” has no past form, so “had to” is the past of both “must” and “have to”.
Student Look at these signs for the guide. This one means you mustn't run.
Friend And that one means you can't use your phone in the library.
New student At my school in Accra, we had to wear a uniform.
Friend Here we don't have to wear one. I can wear my green hoodie every day!
Student But you have to be on time. The notice says pupils must be in class at 8.45.
Asking about a rule: “Can I…?” and “Are we allowed to…?”
To ask if something is OK, say “Can I…?” or “Are we allowed to…?”; to ask if it is necessary, “Do I have to…?”. Short answers repeat the first word.
- “Can I sit here?” “Yes, you can.”
- “Are we allowed to use calculators?” “No, we aren’t.”
- “Do I have to bring a dictionary?” “No, you don’t.”
New student Are we allowed to eat in the science lab?
Student No, we aren't. It's a new rule this term.
Rules on signs: A2 Key Reading Part 1
In Reading and Writing Part 1, you read six short texts (signs, notices, messages) and choose which of three sentences means the same. The right answer often says the same rule in other words. Our own examples:
- “POOL: Students must wear a swimming cap.” → “You need a cap to swim here.”
- “No food in the computer room.” → “You can’t eat in the computer room.”
- “Sports Day: no uniform needed.” → “You don’t have to wear a uniform on Sports Day.”
- Traps: an option with “can” when the notice says “No…”, or with “mustn’t” when something is only not needed.
Common mistakes and how to fix them
After “can” and “must”, the verb has no “to” and no -s; only “have to” keeps “to” (“has to” with he, she and it). Check your writing for these:
- “No running! You don’t have to run.” → “No running! You mustn’t run.”
- “You must to be on time.” → “You must be on time.”
- “She have to take the bus.” → “She has to take the bus.”
- “Yesterday we must stay late.” → “Yesterday we had to stay late.”
Practice: five tips for a new student
This is practice, not an exam task. Write five tips for someone new at your school, with at least three different starts and one “don’t have to”. Our model, then a 10-minute routine:
- “1 You must be at school by 8.30. 2 You can borrow library books. 3 You mustn’t eat in the computer room. 4 You don’t have to wear a uniform on Fridays. 5 Always pack your bag the night before.”
- Minutes 1–4: write your tips.
- Minutes 5–7: a parent or friend hears each tip and says “OK”, “Do it!”, “Don’t do it!” or “No need”.
- Minutes 8–10: as in Speaking Part 1, answer “Tell me something about your school.” out loud, with two rules.
What comes next
Next, use these forms in an email to a friend who is coming to stay. At B1 Preliminary, you explain and compare rules in longer texts.