untryside. the pollution of water is equally harmful. the whole ecological balance of the sea is being changed and industrial wastes have already made many rivers lifeless.
now environmental protection is more pressing than ever before. as we know, massive destruction of environment has brought about negative effects and even poses a great threat to man's existence. indifference to these problems will mean committing suicide. therefore, effective measures should be taken and laws passed to conserve environment. otherwise,man is certain to suffer from the serious consequences caused by this lack of care for his living surroundings.
人和环境
人类有史以来不断改变自然环境，以改善自己的生活方式。人类借助技术工具改变了地球的许多自然特征。他将林地和草原改造成为农田，使江河变成湖泊和水库，用于灌溉或用于水力发电。人类还通过给沼泽地排水、凿石劈山、修建公路和铁路等方式，改变了地球的面貌。
然而，人类改变自然环境并不总是带来有益的结果。今天，空气和水的污染给地球的健康造成越来越严重的危害。每天机动车辆的排气管排出成千上万吨废气。工厂释放的烟雾污染了工业区和周围乡村的空气。水污染同样有害，海洋的整个生态平衡正在受到破坏，工业废水已使许多河流的生物死亡。