70. What has sparked the increasing interest in exercise ? For one thing , people have gained a greater awareness of the need for physical fitness . For another , the constantly improving standard of living enables Chinese people to patronize the increasing number of recreational venues . The main thing perhaps centers on the healthcare and psychological benefits exercise provides .

　　什么引发了人们对锻炼越来越浓的兴趣?一方面，人们更加清楚地意识到保持身体健康的必要性。另一方面，不断提高的生活水平使中国人能够支付增加的娱乐支出。最主要的可能在于锻炼带来的保健和心理上的好处。

　　71. Identifying the reasons for an emerging phenomenon which involves several complicated factors is far from an easy task . For example , some scientists attribute environmental deterioration to a series of natural factors , while others place the blame solely on inappropriate human behavior .

　　要找到涉及许多复杂因素的新现象的原因远非一件易事。例如，一些科学家把环境的恶化归结为一些自然因素，而另一些人把责任都推在人类不适当的行为上。

　　72. One doesn't have to look far to realize the direct correlation between smoking and cancer .

　　人们不用花费很大力气就能发现抽烟和癌症之间的直接联系。

　　73. The explanation for the phenomenon of the rising teenage suicide rate involves many complicated factors . Some attribute the rise to an overemphasis on early success , others point to mounting peer pressure , and still others to confusion

　　over changing social values .

　　对上升的少年自杀率的解释涉及很多复杂的因素。有的人把上升的原因归结为过分强调少年时期的成功，有的人指出是因为不断增长的同伴之间的压力，还有人认为是对不断变化的社会价值的迷茫造成的。