Modals
Use can, could, may, might, should, and must with confidence.
One small word changes the meaning.
Mission brief
Change the meaning of any verb
Modal verbs sit in front of a main verb and change its meaning — turning it into ability, possibility, advice, or obligation.
One small word can completely change what a sentence means.
Core rule
Basic formula
I can swim. · You should study. · We must leave.
The one rule that matters most: after a modal, use the base verb. No to, no -s, no -ing.
She can swims
No -s after a modal.
You should to study
No to after a modal.
I can swimming
No -ing after a modal.
How it works
Can and can't
I can swim.
You are able to do it.
She can speak English.
A skill she has.
Can I borrow your pen?
Asking to be allowed.
How it works
Could
When I was six, I could swim.
An ability you had in the past.
Could you help me?
Softer and more polite than can.
How it works
May and might
May and might both show possibility — something is possible, but not certain.
It may rain later.
Possible, not certain.
She might come tonight.
Possible, not certain.
How it works
Should and shouldn't
You should sleep early.
A good idea.
You should drink more water.
A recommendation.
You shouldn't stay up too late.
A bad idea.
How it works
Must and mustn't
You must wear a seat belt.
Strong obligation or necessity.
You mustn't touch that wire.
Prohibition — it is forbidden.
Important: mustn't does not mean “not necessary”. It means “do not do this”.
How it works
Have to and has to
Have to also shows necessity, and it often comes from a rule rather than the speaker.
have to
I have to finish my homework.
has to
She has to wear a uniform.
Compare it
Which modal, which meaning?
Ability
I can swim.
Possibility
It might rain.
Advice
You should rest.
Strong obligation
You must stop.
Prohibition
You mustn't run here.
Necessity from a rule
We have to wear shoes.
Common mistakes
Error detector
She can swims.
You should to study.
He must goes now.
I can swimming.
She has to wears a uniform.
Real-life English
Before the exam
Aiman I have an exam tomorrow.
Sara You should revise tonight.
Aiman Can I study with you?
Sara Sure. But we must finish before 10.
Test yourself
Quick check
Revision map
Mission summary
Can
ability · permission
Could
past ability · polite request
May / Might
possibility
Should
advice
Must / Mustn't
strong obligation · prohibition
Have to
necessity, usually from a rule
Exam strategy
Exam booster
Decide the meaning first: ability, possibility, advice, or obligation.
After any modal, use the base verb.
Modals never take -s, even with he, she, or it.
Mustn't means forbidden, not optional.
Have to and has to must still agree with the subject.
Worked example: “Students ___ run in the science lab.” Running there is forbidden, so: Students mustn't run in the science lab.
Mission review point
Modals complete
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