)You can spend the night at my flat. We have a spare bedroom.
2)Young people in my country don't have to do military service. It stopped last year.
3)I think everyone should vote at elections. It's our duty as citizens.
4)Maria doesn't have to come if she doesn't want to.
5)I think people shouldn't come to work in jeans. It looks really bad.
6)In the UK children have to stay at school until they're sixteen. It's the law.