1. Choose the correct sentence!
Read the sentences and underline the correct one.
You must be on time for school.
a. You must to be on time for school.
You mustn't be on time for school.
We mustn't eating in class.
b. We mustn't to eat in class.
We mustn't eat in class.
My sister must walk the dog.
c. My sister must walking the dog.
My sister must to walk the dog.
You must to be careful when crossing the road.
d. You mustn't be careful when crossing the road.
You must be careful when crossing the road.
You mustn't to play with a ball in the house.
e. You mustn't play with a ball in the house.
You mustn't playing with a hall in the house