Expressing obligation: must, have to

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Exam day. You must be on time. You mustn't use a mobile phone. You don't have to answer the questions in order. Three little rules — and three different meanings. You already know must and have to; this lesson makes sure you can use them to express an obligation, and tell mustn't from don't have to. So is « you mustn't » the same as « you don't have to »?

🎓في نهاية هذا الدرس ستكون قادرا على:

التعبير عن الإلزام بـ ⁦must⁩ و ⁦have to⁩ متبوعتين بالمصدر
التمييز في النفي بين ⁦mustn’t⁩ (المنع) و ⁦don’t have to⁩ (انتفاء الإلزام)
تصريف ⁦have to⁩ مع الغائب المفرد ⁦(has to)⁩ ونفيه ⁦(doesn’t have to)⁩
كتابة قائمة بما يجب وما يُمنع في امتحان البكالوريا

🔑يفترض هذا الدرس أنّك تتقن:

الأفعال الناقصة متبوعة بالمصدر دون ⁦to⁩
النفي في الحاضر البسيط بـ ⁦don’t, doesn’t⁩
التعبير عن الإلزام في الماضي بـ ⁦had to⁩

1. Must and have to: an obligation

⁦must⁩ و ⁦have to⁩ متبوعتين بالمصدر تعبّران عن الإلزام، أي عن أمر ضروريّ. وهما مترادفتان في الإثبات.

Must and have to + infinitive express an obligation — something that is necessary. In the affirmative, the two are synonymous: « You must study harder » = « You have to study harder ». Must is a modal: it never changes (I must, she must). Have to is a verb: it becomes has to after he, she, it, and it takes do in questions and negatives — Do you have to…? You don't have to… For an obligation in the past, we use had to.

Must in the unit

1. You must study harder, otherwise you won't pass your Baccalauréat with distinction. 2. I must admit my wife and I would have felt much happier if he'd chosen to do something else.

Task 1 — Which modal is synonymous with have to? Rewrite sentence 1 with it.

أيّ فعل ناقص يرادف ⁦have to⁩؟ أعد كتابة الجملة الأولى به.

Must. In the affirmative, both express an obligation: « You have to study harder, otherwise you won't pass your Baccalauréat with distinction. » In sentence 2, I must admit means that Mr Harris feels obliged to say it: the obligation comes from the speaker himself.

2. In the negative: mustn't or don't have to?

في النفي يختلف المعنيان: ⁦mustn’t⁩ تعني المنع، و ⁦don’t have to⁩ تعني أنّ الأمر غير ضروريّ.

In the negative, must and have to are different. Mustn't (must not) means that something is forbidden: it expresses a prohibition. Don't have to (doesn't have to) means that something is not necessary: there is no obligation — you are free to do it or not.

Fill in the blanks with must, have to, should, ought to, or their negatives. There are many possibilities.

In the United States most students who win a scholarship to the university …(1) maintain a certain grade level so as not to lose it. High school students …(2) (not) study all the subjects in the curriculum. They decide for themselves which subjects to take. They …(3) (not) break the codes of honour and conduct of their school. They …(4) be very good at sports because this may earn them a place in a prestigious university.

Task 2 — the answers, and the clue in the text

في كلّ فراغ اسأل: إلزام، أم منع، أم انتفاء إلزام، أم نصيحة؟

(1) have to (or must) — an obligation: if they do not keep a certain grade level, they lose the scholarship.
(2) don't have to — no obligation: « They decide for themselves which subjects to take ».
(3) mustn't — a prohibition: breaking the codes of honour and conduct is forbidden.
(4) should (or ought to) — advice: being good at sports « may earn them a place in a prestigious university ».

Task 3 — Are must and have to similar or different in meaning when they are in the negative? Explain with the text.

هل يتشابه معنى ⁦must⁩ و ⁦have to⁩ في النفي أم يختلف؟ علّل من النصّ.

They are different. « They mustn't break the codes of honour » means that it is forbidden. « They don't have to study all the subjects » means that it is not necessary: they choose. So in the affirmative, must = have to; in the negative, mustn't ≠ don't have to.

3. The rules of the Baccalauréat

قواعد الامتحان: ما يجب فعله، وما يُمنع، وما لا يلزم.

Rules are often written as a list: what you must do, what you mustn't do — and sometimes what you don't have to do.

Do this alone, in writing. Write the rules of the Baccalauréat exam as you see them: three things you must do, three things you mustn't do, and one thing you don't have to do. Then check: is every mustn't a prohibition, and every don't have to a freedom?

اكتب وحدك قواعد امتحان البكالوريا كما تراها: ثلاثة أمور واجبة، وثلاثة ممنوعة، وأمر واحد غير لازم.

A model answer

You must arrive on time. You must bring your identity card. You must write your name on your paper. You mustn't use a mobile phone. You mustn't talk to the other candidates. You mustn't copy from anyone. You don't have to answer the questions in order.

In the exam, obligation is tested by rewriting: « It is forbidden to use a phone during the exam » becomes « You mustn't use a phone during the exam »; « It isn't necessary to come early » becomes « You don't have to come early ». Have three things ready: ① must, have to + infinitive = obligation (has to after he, she, it); ② mustn't = prohibition; ③ don't have to = no obligation. The frequent mistake is to use mustn't for « not necessary »: « You mustn't come » forbids it; « You don't have to come » leaves you free.

What I keep — Must and have to + infinitive express an obligation; in the affirmative they are synonymous (You must study harder = You have to study harder), and has to follows he, she, it. In the negative they part: mustn't forbids (They mustn't break the codes of honour), don't have to frees (They don't have to study all the subjects). For the past, had to.

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