There are some places in the world where great cities once stood. There were gardens, trees and grass. But now these cities have gone and the places are like deserts. Scientists began to study this land to find out what had happened. Many of them believed the land died when the trees were cut down.
Trees help other plants grow and help hold the soil in place. They keep the soil from blowing away. The leaves of trees on the ground keep rainwater from running off. Trees near farms protect growing plants from strong winds.
Once there were hundreds of farms in the Southwestern United States. Then the farms turned into fields of dry dust (尘土). Trees might have saved these farms. But few trees grow in the dry Southwest now.
Now we try to save trees. In many places, when a tree is cut down, a new tree is planted in its place. We do not want the land to die.
參考答案:这个世界上有很多地方曾经矗立着伟大的城市，有着花园、树木和草丛。但是现在这些城市都消失了，这些地方如今变成了沙漠。科学家开始研究这些土地希望可以发现在这里发生过什么事情。大部分科学家认为土地是在树木被砍伐的时候消失得。
树木对于其他植物得成长有着很大帮助，而且可以帮助维持土壤，防止土地被吹走。地面上得树叶阻止雨水流走。农场附近得树木还可以保护正在成长得植物抵抗暴风雨得袭击。
曾经在美国得东南部有着成百上千个农场，结果它们都变成了尘土。树木本可以保护这些农场的，但是现在的干燥的东南部近乎没有任何树木。
现在我们要努力保护树木。在很多地方，一棵树被砍掉，在它原来的地方就立即又种上一棵新的。我们不希望我们的土地死去。
