Choose the sentences, which are CORRECT. Correct the other sentences.
1. You can do housework when you are at school.2. She must take care of her parents.3. The pupils must hurry. The lesson starts in five minutes.4. Passengers mustn't pay for the tickets.5. The girl can go for a walk with her dog in the afternoon.6. The children mustn't behave themselves when they're with guests.7. Drivers can park their cars on lawns.