Modal Verbs
Learn how to use modal verbs to express ability, permission, obligation, possibility, advice, and more. Master can, could, may, might, must, shall, should, will, would.
What are Modal Verbs?
Modal verbs are auxiliary (helping) verbs that express attitude, possibility, necessity, ability, permission, or obligation. They are used with the base form of the main verb and never change form (no -s in third person).
Key idea: Modal verbs add meaning to the main verb. They never take -s, and they are followed by the base form of the verb.
The Main Modal Verbs
| Modal Verb | Function | Example |
|---|---|---|
| can | Ability, permission, possibility | "I can swim." / "Can I go?" |
| could | Past ability, polite request, possibility | "I could run fast." / "Could you help me?" |
| may | Permission, possibility, polite request | "May I come in?" / "It may rain." |
| might | Possibility (less certain than may) | "I might go to the party." |
| must | Obligation, necessity, strong certainty | "You must wear a seatbelt." |
| shall | Suggestions, offers, future (formal) | "Shall we go?" / "I shall return." |
| should | Advice, recommendation, expectation | "You should see a doctor." |
| will | Future, promises, offers, certainty | "I will help you." |
| would | Polite request, hypothetical situations, habit in past | "Would you like coffee?" |
Form Rules
✅ Affirmative
Subject + modal + base verb
"She can speak French."
"He must go now."
❌ Negative
Subject + modal + not + base verb
"She cannot (can't) speak Arabic."
"You must not (mustn't) smoke here."
❓ Question
Modal + subject + base verb?
"Can she speak French?"
"Must we leave now?"
Important: Modal verbs never change form (no -s for third person). They are always followed by the base form of the main verb (without "to").
✅ "He can play guitar." ❌ "He cans play guitar." / ❌ "He can to play guitar."
Functions & Usage
💪 Ability: CAN / COULD
CAN (present ability)
"I can swim." / "She can speak three languages."
COULD (past ability)
"When I was young, I could run fast."
🔓 Permission: CAN / COULD / MAY
CAN (informal)
"Can I borrow your pen?"
COULD (more polite)
"Could I open the window?"
MAY (formal)
"May I come in?"
⚠️ Obligation & Necessity: MUST / HAVE TO
MUST (personal obligation/strong advice)
"You must stop smoking." / "I must call my mother."
HAVE TO (external obligation)
"You have to wear a uniform at school."
❌ Negative: must not (mustn't) = prohibition | don't have to = no obligation
🤔 Possibility: MAY / MIGHT / COULD
MAY (50% chance)
"It may rain tomorrow."
MIGHT (30% chance)
"I might go to the party."
COULD (possibility)
"This could be the solution."
💡 Advice: SHOULD / OUGHT TO
SHOULD
"You should eat more vegetables."
OUGHT TO
"You ought to apologize."
🙏 Polite Requests & Offers: WILL / WOULD / SHALL
WILL
"Will you help me?"
WOULD (more polite)
"Would you like some tea?"
SHALL (suggestions)
"Shall we go for a walk?"
Examples in Context
📖 Ability:
- I can play the piano.
- She could read when she was four.
🔓 Permission:
- Can I use your phone?
- May I leave early today?
⚠️ Obligation:
- You must stop at the red light.
- Students must not use phones in class.
🤔 Possibility:
- It may snow tomorrow.
- I might be late for the meeting.
💡 Advice:
- You should exercise regularly.
- She shouldn't stay up so late.
🙏 Requests & Offers:
- Would you like some coffee?
- Shall we start the meeting?
Common Mistakes to Avoid
❌ Incorrect:
"He cans speak English."
✅ Correct:
"He can speak English."
❌ Incorrect:
"She must to go now."
✅ Correct:
"She must go now."
❌ Incorrect:
"Do you can swim?"
✅ Correct:
"Can you swim?"
❌ Incorrect:
"You don't must go."
✅ Correct:
"You must not go." (prohibition) or "You don't have to go." (no obligation)
Interactive Exercises
Practice what you've learned. Choose the correct modal verb.
Quick Summary
Modal + base verb (no -s, no to)
can go, must study, should try
modal + not + base verb
cannot, must not, should not
modal + subject + base verb?
Can you? Should we? Must I?
💡 Remember: Modal verbs express attitude, possibility, necessity, and ability. They never change form and are always followed by the base verb!