7. It is important for science.

6. It is clean and does not pollute the air.

5. It can help many people in the future.

4. It is good for the economy.

3. Does that matter?

2. I would rather not tell you.

1. It can't be tree.

20. a waste of 浪费……

　　 ☆交际用语☆

19. get killed 丧命；被杀

18. fall asleep 入睡