根据短文理解，从A、B、C、D四个选项中选择最佳一项填空。
What is your greatest dream? We received several different answers to the question.
Zhu Weiqi: I remember the sky was really 1 when I was a child. But now there are more and more 2, and we have begun to lose that sky which looked like a blue diamond(宝石).
Wu Qihang: It is great to see the fast 3 of science, but I would rather see the development of people in China.
Su Yang: Now, some areas are still not peaceful in the world. Many people are 4 and thousands of children cannot go to school. I hope that in the near future, people in there can live a(n) 5 life.
Li Ziliang: I wish that one day I could have my own spaceship. I hope I could 6 a new planet that is suitable for us to live on so that the Earth will not be 7 any more. We can live a happy life both on the new planet and on the Earth.
Chen Xiaoxin: My dream is to travel 8 the world and collect smiling faces, and then 9 them into space. A smile would build up a(n) 10 between us and the aliens.
）可作为火箭发动机的燃料，NH3与NaClO反应可得到肼．