Today the quality of our natural environment has become an important issue.The world population is rising so quickly that the world has become too crowded.We are using up our natural resources and at the same time polluting our environment with dangerous chemicals.If we continue to do this, life on earth cannot survive.

　　现如今我们的自然环境已经成为一个重要问题。世界人口增长如此之快以至于世界已经变得过于拥挤。我们在消耗自然资源的同时危险化学物品污染着我们生存的环境。如果我们继续这样下去，地球上的生物将不能生存。