We are now living in a common home. That is the earth. She provides us with enough food, enough water and enough living room. So we must do everything to protect her. There are lots of big or small, red or green, beautiful gardens around us .But there are still some other lands bare of grasses or trees on the earth. Some people may ask why not led all lands covered with trees, flowers and grasses? Why not prevent the lands from being desert? Why not prevent the air from being polluted? And why not prevent the earth from being poisoned? Yes! Our environment is being polluted faster than nature and man s efforts can prevent. Time is bring us more people, and more people will bring us more industry. So many trees will be cut down, and more large cities will be set up. Lots of waste material, in return, is produced and harms the environment. So some experts declare that the balance of nature is being destroyed. The survival of man is in danger. We feel really sad about it. What can we do to solve this problem? We must forbid cutting down trees and forbid killing animals and pouring waste water into rivers and so on. We ll never destroy the balance of nature. Let s get along well with all animals. Let the trees, flowers and grasses come back to our home. Because we have only one home --- the earth.