Modal Verbs – Possibility, Permission, Advice, and Obligation

📘 Rule Summary

Modal verbs are special auxiliary verbs used before the base form of the main verb to express ability, permission, advice, obligation, possibility, or necessity. They include: can, could, shall, should, will, would, may, might, must, ought to, need to, dare.

📝 Examples

You must wear a seatbelt.

I can swim.

She should call her mother.

Could you help me, please?

📖 Explanation

🧠 Day 23: Modal Verbs – Helping Words That Add Power to Sentences

🧩 Modal verbs are like mood buttons for English sentences. They tell us if something is possible, necessary, polite, or optional.

🌱 Level 1 – Beginner: What Are Modal Verbs?

🔹 What Makes a Verb Modal?

Feature	Modal Verbs
Never take “-s”	❌ He cans / ✅ He can
Followed by base verb	✅ I can go
No “do/does/did” for questions or negatives	✅ Can you swim? ❌ Do you can swim?
No infinitive or participle forms	❌ to can, canning – don’t exist

🔸 Common Modals with Functions

Modal	Function	Example
can	ability / permission	I can ride a bike.
could	past ability / polite request	I could help you.
may	permission / possibility	May I come in? It may rain.
might	less certain possibility	We might be late.
must	strong obligation / certainty	You must obey. He must be tired.
should	advice / recommendation	You should study more.
will	future / certainty	I will call you.
would	polite offers / imaginary	Would you like tea? I would go if I could.

🌿 Level 2 – Intermediate: Usage Differences and Comparisons

🔸 Can vs. Could

Can = ability now

I can drive.

Could = ability in the past OR polite

I could run fast as a child.
Could you help me?

🔸 May vs. Might

May = formal, higher possibility

It may rain.

Might = lower possibility

It might snow.

🧠 In spoken English, both are often interchangeable.

🔸 Must vs. Have to

Must = speaker’s own rule or strong advice

You must see this movie!

Have to = external obligation

I have to go to work (my boss expects it).

🔸 Should vs. Ought to

Both mean advice

You should/ought to eat healthier.

“Ought to” is more formal or old-fashioned.

📘 Real-Life Mini Story – A Day at Work

I had to wake up at 6 AM because I must attend an urgent meeting.
I could have taken a cab, but I should save money, so I took the bus.
I might be late, but I mustn’t panic.
When I reached, the manager said, “You should prepare better next time.”
I said, “I will do that, sir.”

🧠 See how many modals express rules, regrets, hope, and intentions?

🧨 Common Errors with Modal Verbs

❌ Incorrect	✅ Correct	Why
He cans swim.	He can swim.	No “s” with modals
I can to swim.	I can swim.	No “to” after modal
She musted go.	She must go.	Modals don’t take past form
Do you can help me?	Can you help me?	Use modal directly
I must to finish this.	I must finish this.	No “to” after modal

📏 Structure of Sentences

Type	Structure	Example
Affirmative	Subject + modal + base verb	She can dance.
Negative	Subject + modal + not + base verb	He must not lie.
Question	Modal + subject + base verb?	Can you help me?

🧪 Polite Requests Using Modals

Can you help me? (casual)
Could you help me? (polite)
Would you mind helping me? (more polite)

🧠 The more polite = the softer the modal!

🌳 Level 3 – Advanced: Subtle Usage

🔸 Modals of Deduction (certainty)

Modal	Meaning	Example
must	95–100% sure	He must be tired.
might / may	50–70% sure	She might be late.
can’t / couldn’t	sure it’s false	That can’t be true.

🔸 Past Modals: could have, should have, must have

Modal	Function	Example
could have	unreal ability	I could have won.
should have	regret	You should have called.
must have	deduction	He must have forgotten.

🔸 Modals in Conditional Sentences

If I had more time, I would help you.
You should study, or you might fail.

🧠 Practice Transformation

Turn these into modal-based sentences:

You are required to submit the form.
→ You must submit the form.
Maybe she is sleeping.
→ She might be sleeping.
It’s a good idea to drink water.
→ You should drink water.
He wasn’t able to reach.
→ He couldn’t reach.
Is it okay if I leave now?
→ May I leave now?