Complete the sentences with must, mustn’t or don’t / doesn’t have to.

1 I _______ write to Ella and say thank you for the present.
2 You _______ tell him about the party. It’s a surprise!
3 Mark _______ go to work this week. He’s on holiday.
4 We _______ finish our homework before we go online on a school day. It’s a house rule.
5 You _______ turn off the computer. I’m going to use it in a minute.
6 People _______ feed the birds in the park. It’s very bad for them to eat bread.