着经济的快速发展，大城市中的高楼越建越多，道路越修越宽，但树木却越来越少。以国庆五十周年为契机，国家号召各大城市努力整顿市容，拆除违章建筑，增加绿化面积。这无疑是个造福子孙的明智之举。请你以下面三句话分别作为三段段首主题句，以绿化我们的城市为题，写一篇文章。

　　With industries and business developing quickly, the number of trees in many big cities has dramatically reduced.

　　Making cities greener has many advantages.

　　Making our cities greener requires nationwide efforts.

　　【范文】

　　Make Our Cities Green

　　With industries and business developing quickly, the number of trees in many big cities has dramatically reduces. Efforts are being made to prevent people from cutting more trees. But a lot of trees are being destroyed by people who have never thought of the importance of green plants.

　　Making cities greener has many advantages. First, it can make our air cleaner. Some researchers have proved that trees can reduce the amount of carbon dioxide in the atmosphere through absorption. Second, it can make our cities more beautiful. With trees and flowers everywhere, living conditions can be improved. Finally, it can produce timber----an effective way to solve the problems of limited supply of natural resources.

　　Making our cities greener requires nationwide efforts. People in every field should not only know about the importance of keeping the quality of urban environment, but also take common action to plant more trees and flowers so as to improve our living conditions.