用括号中词语的正确形式填空。
1. It is ______ (polite) to leave without saying goodbye to the host.
2. These containers can be used again. So they are called ______ (use) containers.
3. The doctor said the old man's condition was ______ (hope) because the operation was not successful.
4. Those small factories are causing a lot of ______ (environment) ______ (pollute) with all their noise
and smoke.
5. The more exercise young students take, the more ______ (energy) they will become.
6. The ______ (nation) emblem (国徽)of England is a rose.
7. The lecture was ______ (agree) to Tom, so he fell asleep quickly.
8. Human beings are ______ (create) animals. They have created a lot of wonders.