They ___ do their work because it is very easy
can
He is so tired! He ____ get up!
can't
We ____ (neg) get the tickets in advance. We ____ (aff) get them at the door
don't have to/can OR can't/have to
We ____ forget her birthday or she'll be very upset
mustn't (can't)
I ____ find my glasses anywhere! Have you seen them?
can't
I'm afraid I ____ come to your party. Sorry!
can't
You _____ bring any food on the outing as the school will provide a packed lunch.
don't have to
The doctor says I _____ eat more vitamin C.
have to (must)
