English — Grammar: Modals — Expressing Ability, Permission, Obligation and Advice — 2nd Year Secondary

Modal verbs (can, could, may, might, must, should, ought to, etc.) are auxiliary verbs that express different meanings such as ability, permission, obligation, possibility and advice.

I. Ability

Can (present): “I can speak French.”
Could (past): “I could swim when I was five.”
Be able to (all tenses): “I will be able to help you tomorrow.”

II. Permission

Can (informal): “Can I borrow your pen?”
May (formal): “May I come in?”
Could (polite): “Could I use your phone?”
Be allowed to: “Students are allowed to use the library.”

III. Obligation

Must (strong obligation – personal): “I must study for the exam.”
Have to (external obligation): “We have to wear a uniform at school.”
Mustn’t (prohibition): “You mustn’t smoke here.”
Don’t have to (no obligation/choice): “You don’t have to come if you don’t want to.”

IV. Advice

Should / Ought to: “You should see a doctor.” / “You ought to apologize.”
Had better (strong advice): “You had better leave now.” (implies negative consequences)

V. Possibility and Probability

Modal	Probability	Example
Must	95% sure (certain)	He must be at home (lights are on)
May/Might/Could	50% (possible)	It might rain tomorrow
Can’t	99% sure (impossible)	He can’t be at school (he’s sick)

VI. Exercises

1. Fill in can/could/must/mustn’t: “You ___ park here – it’s forbidden.”
2. Choose: “You should / mustn’t eat too much sugar – it’s bad for you.”
3. Rewrite: “It’s not necessary to finish today.” (Use don’t have to)

For more grammar lessons, see Future Continuous and Future Perfect and Reported Speech.

English — Grammar: Modals — Expressing Ability, Permission, Obligation and Advice — 2nd Year Secondary