1. Many people speak English in the world. (Đổi sang câu bị động)
→ English is spoken by many people  in the world.
2. The man is sitting next to me. He is my father's friend.
→ The man who is my father's friend  is sitting next to me
3. times/ Every milk bottle /reused/ can be/ /thirty/. (Sắp xếp lại thành câu dúng)
->Every milk bottle can be reused thirty times 
4. Ba is studying very hard because he doesn't want to fail in the exam. (so as (not) to")
- Ba is studying  very hard so as not to fail in the exam.