Помогите исправить предложения:
1. It's Sunday — we mustn't go to school.
2. He did must pay a fine.
3. He's carrying a bag full of letters — he can be the postman.
4. Who's that at the door? It mustn't be Paula because she's at work.
5. He doesn't like confined spaces — he must to have claustrophobia.
6. He might arrives late.