选择方框内的单词完成句子。

1. The experiment is really ___________.

2. The population has __________ in the last few years.

3. I'm surprised to hear the __________ news.

4. The quality of ________ is very important on sale.

5. We should try our best to protect __________ animals.

6. lemons are kind of __________ .

简述防烟排烟系统的半年检查内容和要求。