根据句意及汉语提示完成句子。

1. The chemical factories _____ (生产) terrible gas.

2. Each year people pour _____ (废物) into rivers, lakes and so on.

3. There are _____ (几个) students reading books over there.

4. Do you know he has _____ (参军) for five years?

5. Loud noises can cause high _____ (血) pressure as well.