Turn these sentences into passive voice

Ex1. Turn these sentences into passive voice 
1. My father waters these flower trees every morning.
2. John invited Fiona to his birthday party last night.
3. Her mother is preparing the dinner in the kitchen.
4. We should clean our teeth twice a day.
5. Our teachers give us a free period this Saturday to prepare the festival. 
6. He often does exercises every night.
7. She usually decorates the room at weekends.
8. Daisy always sings country songs.
9. She often gives her sister sweets.
10. Nam and Peter often water these trees. 
11. They produce cars in this country.
12. We don’t allow smoking in this restaurant.
13. Do pupils clean the room every day?
14. People invented the wheel thousands of years ago.
15. My father waters these flower every morning