根据句子意思，用括号中所给词的正确形式填空，每空填一词。

1. It's ________ (friendly) of him to say such bad words to his classmates.

2. Millie, I've left my dictionary at home. May I use ________ (you)?

3. The ________ (shelf) in the library are very old. We need to buy some new ones.

4. We hope the weather will be fine, but it is getting even ________ (bad).

5. There will be less ________ (pollute) in our city if we take action to protect the environment.