Grammar: Modal Verbs (Present)

Modals are auxiliary verbs that express concepts like ability, permission, obligation, advice, and possibility. They are followed by the base form of a verb.

Can / Can't

Ability: He can speak three languages.
Permission: Can I use your phone?
Possibility: It can be cold in winter.
Prohibition (Can't): You can't smoke in here.

Should / Shouldn't (Advice)

Used to give advice or a recommendation. It is not as strong as "must".

You should see a doctor if you feel sick.
He shouldn't spend so much money on video games.

Must / Have to (Obligation)

Must: Internal obligation (speaker feels it's necessary). *"I must finish this report today."*
Have to: External obligation (a rule or law). *"You have to drive on the right."*
Mustn't: Strong prohibition (it is forbidden). *"You mustn't cheat on the exam."*
Don't have to: Lack of obligation (not necessary). *"You don't have to come if you don't want to."*

Can / Can't

Should / Shouldn't (Advice)

Must / Have to (Obligation)

Practice this module interactively