普通高中课程标准实验教科书 英语必修1 Unit 3 Reading

　　Several months before our trip, Wang Wei and I went to the library. We found a large atlas with good maps that showed details of world geography. From the atlas we could see that the Mekong River begins in a glacier on a Tibetan mountain. At first the river is small and the water is clear and cold. Then it begins to move quickly. It becomes rapids as it passes through deep valleys, travelling across western Yunnan Province. Sometimes the river becomes a water fall and enters wide valleys. We were both surprised to learn that half of the fiver is in China. After it leaves China and high altitude, the Mekong becomes wide, brown and warm. As it enters Southeast Asia, its pace slows. It makes wide bends or meanders through low valleys to the plains where rice grows. At last, the fiver delta enters the South China Sea.