Проверьте пожалуйста

1. I must....... !  
2. правильно 
3. верно
4. тут 2 варианта верны - have to/don't have to -  в зависимости от смысла

1. I must study foreign languages, because I want to travel around the world.
2. We have to wear uniform at school.
3. My father doesn't have to work on weekends.
4. You have to buy a ticket to travel by train.
4. You don't have to buy a ticket to travel by train.