阅读下面三部分内容，从各小题所给的四个选项中选出能回答问题所提问题或完成所给句子的最佳答案。
I used to live in a small town with trees all around. It is about thirty years since I left my hometown. But I still remember what it was exactly like. And I often “see” it in many of my dreams. My hometown is a beautiful place. It stands beside a wide river and is rich in fish and rice.
But in the old days it was a poor and backward little town. Many people had no work. They lived a hard life. There was no tall building and the only street was narrow. But trees and flowers made the town beautiful. Just outside the town, there was a river. You could see different kinds of fish swimming in the clear water. People here lived a simple life.
Since a new policy(政策) was taken by the government, great changes have taken place there. The streets have been widened. Factories, schools, hospitals, cinemas and theatres have been built one after another. People's life is greatly improved. You can see tall buildings, big department stores and factories everywhere. Different kinds of cars and buses are running in the wide streets.
But with the development of the industry(工业), we have fewer trees. Air and water pollution is becoming more and more serious. And there are also other problems. We should try our best to make it richer. At the same time, we must do something to stop pollution and make our town even more beautiful.
