Modal Auxiliaries: Can, May, Must, Should – 1st Year Literary Stream – Algeria

Modal Auxiliaries: Can, May, Must, Should

Modal auxiliaries are special verbs that express possibility, ability, permission, obligation, or advice. They are used before the base form of the main verb and do not change form for different subjects. Understanding modals is essential for expressing nuanced meanings in English.

Can and Could

Can is used for: ability (I can swim), permission (Can I open the window?), possibility (It can rain in winter).
Could is the past of can: past ability (I could run fast when I was young), polite requests (Could you help me please?), possibility (It could be true).

May and Might

May is used for: formal permission (You may enter), possibility (It may rain later), wishes (May you be happy!).
Might expresses: less certain possibility (It might rain, but I’m not sure), polite suggestions (You might try calling him).
The difference: May expresses a stronger possibility than might. Example: He may come (50% chance) vs He might come (30% chance).

Must and Have to

Must expresses: strong obligation (internal – from speaker), necessity (You must study for the exam), prohibition in negative form (You must not smoke here), logical deduction (He must be at home – I see his car).
Have to expresses external obligation (rules, laws, external authority): I have to wear a uniform at school. In the past: had to. In negatives: don’t have to (no obligation, not prohibition).

Should and Ought to

Should is used for: advice and recommendations (You should see a doctor), expectation (The train should arrive at 5pm), mild obligation (You should apologize).
Ought to has the same meaning as should but is less common and more formal: You ought to respect your parents.

Other Modals

Will – prediction, promise, willingness (I will help you).
Would – polite requests (Would you like some tea?), past habits (When I was young, I would visit my grandmother every summer).
Shall – suggestions (Shall we go?), offers (Shall I open the door?) – mainly British English.

Modal Perfect (Have + Past Participle)

Must have done – certainty about the past (He must have left).
Can’t have done – impossibility (He can’t have said that).
May/Might have done – possibility (She may have forgotten).
Could have done – past ability not used (I could have won).
Should have done – past advice not followed (You should have studied).

Exercises

1. Choose the correct modal: You (must/should) see a doctor if you feel sick. It’s a good idea.
2. Rewrite the sentence: It is necessary for students to do their homework. (Use must)
3. Complete: She looks happy. She (must/can’t) have passed the exam.

For more English lessons, check Tenses Review: Present, Past and Future and Conditional Sentences: Types 1, 2, 3.

📍 دروس مشابهة

• اللغة الإنجليزية — Past Simple: Regular and Irregular Verbs — 1st Year Middle School — Algerian Curr
• اللغة الإنجليزية — Comparative and Superlative Adjectives — 1st Year Middle School — Algerian Curric
• English — Verb to Be: Affirmative, Negative and Interrogative Forms — 1st Year Middle School — Alger
• English — Numbers from 1 to 100: Cardinal and Ordinal with Exercises — 1st Year Middle School — Alge