1) Why did you have to buy so many chairs?
2) You have to look after this tree very carefully.
3) She doesn't have to correct my mistakes.
4) We should invite our cousins to the wedding.
5) She shouldn't go outside without an umbrella today.
6) The boys must wash their socks every evening.
7) My son mustn't play with a lighter.
8) Can I have a day-off?
9) You must not shout in the museum.
10) He could have gone to the station.
