Đổi các câu sau sang bị động

Đổi các câu sau sang bị động
1. John invited Fiona to his birthday party last night.
2. Her mother is preparing thể dinner in the kitchen.
3. Our teachers have explainde the English grammar.
4. We should clean our teeth twice a day.
5. Thet will hold the meeting before May Day 
6. The teacher is going to tell a story
7. Mary is cutting thể cake now

8. Someone will tell him that news