English – Expressing Obligation and Prohibition: Must, Have to, Mustn’t – BAC

Expressing Obligation and Prohibition: Must, Have to, Mustn’t

Expressing obligation, necessity, and prohibition is an important grammar topic for the BAC exam. Different modal verbs express different degrees of obligation.

Expressing obligation:

• Must + base verb: Strong obligation (from the speaker’s perspective). Ex: “You must wear a seatbelt.” / “Students must respect the rules.”
• Have to + base verb: External obligation (rules, laws, circumstances). Ex: “I have to wear a uniform at school.” / “She has to take the bus every day.”
• Need to + base verb: Necessity. Ex: “You need to study for the exam.”
• Should/ought to + base verb: Advice/recommendation (not strong obligation). Ex: “You should see a doctor.”

Expressing prohibition:

• Mustn’t/must not + base verb: Strong prohibition (it’s forbidden). Ex: “You mustn’t cheat on exams.” / “You must not smoke here.”
• Can’t/cannot + base verb: Prohibition/not allowed. Ex: “You can’t park here.”
• Don’t have to + base verb: Lack of necessity (not prohibition). Ex: “You don’t have to come early.” (it’s not necessary)

Important distinction:

“Mustn’t” = prohibited (دون’t do it)
“Don’t have to” = not necessary (you have a choice)

BAC Example 2023:

“Choose the correct option: ‘You (mustn’t/don’t have to) bring your own book; the school provides them.’ → ‘don’t have to'”

Similar Lessons

• Modal Verbs: Can, Could, May, Might, Must, Should
• Making Suggestions: Let’s, Why don’t we, How about

📍 دروس مشابهة

• English — Present Continuous Tense — Form and Use — 3rd Year Middle School — English Language — Algerian Program
• English — Countable and Uncountable Nouns: Quantifiers (Some, Any, Much, Many) — 1st Year — Literary Stream
• Expressing Ability (Can, Could, Be able to) — Grammar Rules and Exercises — English 3rd Year Middle School — Algerian Curriculum