Giúp mình với mọi người ơi! VI. Change the following sentences into passive voice. 1. My sister is preparing the lunch in the kitchen. 2. My grandfather waters these plants every morning. 3. They were buying a book at 9 am yesterday. 4. They are building several new schools in our town. 5. The Browns are going to paint this house and these cars for Tet holiday 6. Sam killed a lion last week. 7. I can’t see the words on the board  8. The students have discussed the pollution problems since last week. 9. They will hold the meeting before May Day. 10. She had finished her homework before she went to bed.