obligation
must/mustn't
must/mustn't
There is no homework, so I ______ go out with you this afternoon. (CAN, CAN'T)
can
At school, we ____ wear uniforms.
have to
You ____ turn on the central heating. It's automatic. (mustn't, don't have to)
don't have to
You ____ go to the doctor if you are ill. (CAN, MUST)
must
Anne _____ ride a bike because she is only three years old. (CAN, CAN'T)
can't
you ____ wait for me. I can ride all by myself later.
don't have to
You _____ play on the road. There are a lot of cars. (MUST, MUSN'T)
mustn't
Children _____ bring many books everyday.
don't have to
Please feel free to come in. (No eating inside.)
You _____ enter.
You _____ eat inside.