2 Year Bac (الثانية باكالوريا) Lessons July 28, 2026

Modal Verbs — 2 Bac Grammar

My Teacher July 28, 2026
2nd Year Bac · Unit 2 · Grammar

Modal Verbs

Learn to express ability, obligation, advice, possibility, and deduction — the modals the exam tests most.

1

What are modal verbs?


Modal verbs are small helper words — can, could, may, might, must, should — that go before the main verb to add meaning: ability, permission, obligation, advice, or possibility. They never change form and are always followed by the base verb (no “to”, no “-s”, no “-ing”).


ما هي الأفعال الشرطية (Modal Verbs)؟
الأفعال الشرطية هي كلمات مساعدة صغيرة — مثل can, could, may, might, must, should — توضع قبل الفعل الأساسي لإضافة معنى: القدرة، الإذن، الإلزام، النصيحة، أو الاحتمال. لا تتغير هذه الأفعال أبدًا، وتُتبع دائمًا بالفعل في صيغته الأساسية (بدون “to”، وبدون “s”، وبدون “ing”).

Golden rule
Modal + base verb, always. She can swim. (not “cans” or “to swim”) — the only exception is have to, which changes like a normal verb: he has to go.

2

Ability and permission


Use these modals to talk about what someone is able to do, or is allowed to do.

Ability

can — present ability
I can speak English.

could — past ability
I could swim at five.

be able to — all tenses
She’ll be able to drive soon.

Permission

can — informal permission
You can leave early.

may — formal permission
May I come in?

could — polite request
Could I ask a question?


3

Obligation, necessity and advice


These modals are the most exam-tested group. The exact word you choose changes the meaning.

Strong obligation
must (I decide it’s necessary)have to (a rule or fact makes it necessary)

No obligation
don’t have toneedn’t (it isn’t necessarybut you can if you want)

Prohibition (forbidden)
mustn’t (it is forbidden — do NOT do it)

⚠️ The most confused pair
Mustn’t = forbidden. You mustn’t smoke here. (Don’t do it!)
Don’t have to = not necessary, but allowed. You don’t have to come, but you can. These are opposite meanings — never mix them up.

💡 Must vs. have to
Must often shows the speaker’s own feeling: I must call my mother. Have to shows an outside rule: Students have to wear a uniform. In everyday use they’re often interchangeable, but the exam likes this distinction.

Advice — should / ought to
You should revise more before the exam. You ought to see a doctor. (“Should” is far more common than “ought to”.)

4

Possibility and deduction


Modals also let you guess or judge how likely something is — about now, or about the past.

1

Certainmust (positive) / can’t (negative): He must be tired. / She can’t be serious.
2
Possiblemay / might / could: It might rain later.
3
About the past → add have + past participle: He must have missed the bus.

Exam favourite: past deduction
must have + past participle = almost certain it happened. can’t have + past participle = almost certain it didn’t. might/could have + past participle = maybe it happened. She must have studied hard — she got full marks.

5

A worked example


Sentence

My friend looks tired today; he must have stayed up late revising.

He can’t have finished the exam already — it’s only been ten minutes.

She might have forgotten about the meeting.

What it means

Strong deduction — almost certain (past).

Strong negative deduction — almost impossible (past).

A guess — maybe true, not certain (past).


6

Common mistakes to avoid


⚠️ Watch out
She musts go. → ✅ She must go. (modals never add -s)

He can to swim. → ✅ He can swim. (no “to” after most modals)

You mustn’t to worry, it’s not necessary. → ✅ You don’t have to worry. (mixing up mustn’t and don’t have to)


✏️

Your turn — choose the correct modal

  1. 1. I ___ speak three languages.

  2. 2. You ___ smoke in the hospital — it’s forbidden.

  3. 3. You ___ come to the party if you don’t want to — it’s optional.

  4. 4. Students ___ wear a uniform at this school — it’s the rule.

  5. 5. She looks exhausted; she ___ have worked all night.

  6. 6. It’s only 8am, he ___ have arrived already — the flight lands at 10.

  7. 7. It ___ rain later — the sky looks cloudy but it’s not certain.

  8. 8. You ___ revise more if you want to pass.

  9. 9. Choose the correct sentence.

  10. 10. “He must have missed the bus” expresses ___.

  11. 11. Choose the correct sentence.

  12. 12. “Could I ask a question?” is an example of ___.

✏️ Your turn ✍️

Complete each sentence with the modal that best fits the meaning in brackets:

  1. You ___ arrive on time for the exam. (strong obligation)
  2. She ___ be at home — I saw her leave an hour ago. (certain it’s NOT true)
  3. You ___ bring your ID card, but it’s a good idea. (not necessary)
  4. He ___ have forgotten our meeting. (a guess about the past)
  5. ___ I open the window, please? (polite permission)

Watch: Modal Verbs Explained
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A one-page summary of modal verbs — ability, obligation, advice, possibility, and deduction. Save it and revise before your exam.

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