热带雨林是一个具有无限潜力的医药百宝箱，2000种热带雨林植物可能有助于抗癌，在当今的药品市场上，每125种从植物提取的药品中就有15种来自于热带雨林。除了植物，热带雨林所独有的珍稀鸟类和动物也在以每年一种的速度灭绝。
在如此严峻的事实面前，毁林事件仍旧频频发生。原因何在?热带雨林通常位于人口过多的贫穷国家，这些国 家的政府无力阻止人们毁坏雨林。政府无钱帮助穷人，所以当穷人们以砍伐树木为生时，他们只能视而不见。另外，对于这些国家来说，珍贵的木材和其他资源是重 要的外汇来源，他们急需外汇偿还外债、购买国外设备和其他物品。
如何解决这一问题?富裕的国家有责任帮助那些贫穷的国家取消外债、发展经济，并教育贫困国家的人们正确对待雨林，合理科学地利用雨林。富裕国家也可以减少使用木材产品。总之保护雨林已刻不容缓。
本课主要语言点
1.rainforests are being cut and burned from brazil to indonesia at such a rate that they could well disappear from the earth`s surface before the year 2050。
“are being cut and burned”是现在进行时被动语态。如：
1)the problem is being discussed now. (这个问题现在正在讨论。)
2)the car is being repaired by mr. smith. (那辆车正由史密斯先生修理。)
“at such a rate that” (以这样的速度(砍伐、焚烧)以致于…)。我们曾讲过程度副词such和so的区别。一般来说，such的后面接名词，而so的后面接形容词或副词。如：
1)he spoke for such a long time that people began to feel bored. (他讲了那么长时间，人们开始觉得厌烦了。)
2)he made such a rapid progress that both his teachers and his parents were happy。(他取得了飞快的进步，他的老师和父母都觉得高兴。)
3)it was such a fine day that we decided to go for a walk. (天气这样好，我们打算去散步。)
4)the work was so difficult that i couldn`t finish it in 2 hours. (这项工作太难，两小时内我完不成。)
5)she spoke so fast that i could catch her. (她讲话太快，我没听懂他的意思。)
“they could well disappear” 他们很可能消失。well在本句中的意思是“很可能的，很”。如：
1)it might well turn out true. (这很可能会成为真的。)
2)it`s well worth trying. (这很值得一试。)
3)he must be well over forty. (他很可能大大超过四十岁了。)
2.they are being cleared for valuable timber and other resources to speed up the economic growth of the nations in which they are located。
本句中的clear用作动词，意思是remove (清除)，如：