I. Change the following sentences into the passive. (Chuyển các câu sau sang bị động) 6. Mary sent me this letter two days ago. -> I _________________________________________ 7. People make compost from vegetables. -> Compost _________________________________ 8. You must finish this work before Sunday. -> This work _________________________________ 9. She hasn't used this bicycle for a long time. -> This bicycle ________________________________ 10. I saw a strange man in my garden yesterday. -> A strange man _______________________________ 11. They clean the floor every morning. -> The floor __________________________________ 12. They will solve the problem soon. -> The problem _______________________________ 13. They break the glass into small pieces. -> The glass __________________________________ 15. They made these cars in the USA. -> These cars __________________________________ 16. People have used the Internet all over the world. -> The Internet ________________________________ 17. We planted many trees in the school garden. -> Many trees _________________________________ 18. Someone has taken my book away. -> My book ___________________________________ 19. He didn't help me with my homework. -> I ___________________________________________ 20. We have learnt English for three years. -> English ______________________________________ 21. My father often reads books before bedtime . -> Books _______________________________________ 22. Lan bought some comic books for her brother . -> Some comic books ____________________________ 23. My sister received a letter yesterday . -> A letter ____________________________________ 24. She can solve the problem in just 2 minutes . -> The problem _______________________________ 25. Nowadays people use electricity for lighting. -> Electricity __________________________________