câu bị động viết lại các câu sau( bài tập về thì hiện tại đơn và quá khứ đơn) giải thích tại sao làm như vậy

Here are the passive voice rewrites of the sentences: 1. Animals are used as medicines (by them). 2. An interesting lesson was taught by Mr. Nam yesterday. 3. The parcel was not sent (by her). 4. A tree is grown each day (by our class). 5. He was seen last Sunday (by us). 6. Two letters were written last night (by her). 7. She was not visited yesterday (by me). 8. Rice is not grown on this farm (by people). 9. The tickets were not shown at the theater (by them). 10. Are goods delivered every day (by them)? 11. Are fruits sold by Mary in the supermarket? 12. Is English learned by students on Monday? 13. Was a road built in our area (by them)? If you need an explanation of how to form the passive voice, please let me know!