21. The other passengers will get on the bus as soon as we leave. 22. I turned off the lights before I left the room. 23. I won't return my book to the library until I finish my project. 24. The frying pan caught on fire while he was making dinner. 25. I will take a walk in the park as soon as I finish my study. 26. She dropped a cartoon of eggs when she was leaving the shop. 27. He had never heard about Halloween before he took part in a Halloween party last year. 28. Shakespeare had written more than 37 plays before he died in 1616. 29. Mr. Thanh won't answer your email until he has some free time. 30. Susan feels nervous whenever she chews her nails. A. LISTENING Exercise 1: 1. D - Pollution is nothing 2. A - Big factories 3. C - rivers 4. D - The Earth Exercise 2: 1. A - Global warming 2. C - They are dying 3. B - They are melting 4. C - It is making places warmer or colder