Modal verbs and their negatives


Modal verbs and their negatives
positive negative
must (used for a personal opinion)
He must be crazy.
can't
He can't be crazy.
must / have to / has to (used for obligation)
You must be there at 8 o'clock.
You have to be there at 8 o'clock.
don't have to / needn't = something is not necessary
You don't have to be there at 8 o'clock.
You needn't be there at 8 o'clock.
can (used for ability)
I can play the guitar.
can't / cannot
I can't play the guitar.
can (used for possibility)
You can smoke here.
can't / cannot / mustn't
You can't smoke here.
You mustn't smoke here.