听对话, 根据对话内容完成下列句子，每空词数不限。对话读三遍。
1. What is Kelly reading?
She is reading a book about the ________________.
2. What does Kelly think cities will be like?
Cities will be more ________________ and polluted.
3. If there are fewer trees, what will happen?
If so, the environment will be ________________.
4. Where does Kelly want to live?
She wants to live on the ________________.
5. Why will there be fewer jobs for people?
Because more ________________ will do the same jobs as people.