Modal Verbs
Modal Verbs are special auxiliary verbs that express the speaker’s attitude or mood toward an action. They show possibility, ability, necessity, permission, obligation, certainty, and more.
- She can swim very well. (ability)
- It might rain later. (possibility)
- You must wear a seatbelt. (obligation)
Subject + Modal Verb + Base Form of Main Verb
Example: She can dance. / They must leave soon.
❗ Modals are always followed by the base form of the verb (no “to” or “-s”).
- They never take -s in the third person (❌ He cans, ✅ He can).
- They are followed by a bare infinitive (base verb without “to”).
- They do not have all verb forms (no past participle, infinitive, etc.).
- They express the speaker’s attitude or opinion.
1. Can – Ability / Permission / Possibility
Ability: I can speak three languages.
Permission: You can go now.
Possibility: Anyone can make mistakes.
2. Could – Past Ability / Polite Request / Possibility
Past Ability: When I was a child, I could run fast.
Polite Request: Could you help me, please?
Possibility: It could rain tomorrow.
3. May – Permission / Possibility / Wish
Permission: You may enter now.
Possibility: It may snow tonight.
Wish: May you have a long life!
4. Might – Weaker Possibility
Possibility: She might come to the party (50-50 chance).
Suggestion: You might try restarting your laptop.
5. Must – Obligation / Deduction
Obligation: You must wear a helmet.
Deduction: She must be tired after the trip. (Logical conclusion)
6. Shall – Future Intention / Suggestion (Formal)
Future: We shall meet again soon.
Suggestion: Shall we go out for coffee?
7. Should – Advice / Expectation / Duty
Advice: You should eat more vegetables.
Expectation: The train should arrive at 6.
Duty: Students should respect their teachers.
8. Will – Future / Willingness / Promise
Future: I will call you tomorrow.
Promise: I will help you.
Habit: He will often talk for hours.
9. Would – Politeness / Habit in the Past / Imaginary Situations
Politeness: Would you like some tea?
Past Habit: When I was young, I would play outside every day.
Imaginary: I would travel if I had money.
10. Ought to – Moral Duty / Advice
You ought to help your parents.
We ought to respect the law.
We can use modals with have + past participle to talk about the past.
- He must have forgotten the meeting. (deduction)
- You should have studied harder. (regret/advice)
- She could have won the race. (missed possibility)
❌ Wrong: He can to swim.
✅ Correct: He can swim.
Never use “to” after a modal verb.
❌ Wrong: She musts go now.
✅ Correct: She must go now.
Modals never take -s in third person.
❌ Wrong: I will can go there.
✅ Correct: I will be able to go there.
Modals cannot be combined; use an alternative phrase.
- Can/Could → Ability, Permission, Possibility
- May/Might → Permission, Possibility
- Must → Necessity, Deduction
- Shall/Will → Future, Willingness
- Should/Ought to → Advice, Duty
- Would → Politeness, Imaginary Situations
- Modals + Base Verb → Always rule of thumb ✅