A. 根据句意，用括号内所给词的正确形式填空。
1. Earth is becoming more and more __________ (crowd).
2...__________ (hope), we can start again.
3. This pair of boots looks very ____________ (fashion).
4. There will be no ___________ (pollute) on Mars.
5. ____________ (science) are working hard to make the dream become true.
6. There is an _________ of oil paintings in the museum. (exhibit)
7..I have decided to write a __________(complain) letter for my broken bike.
