一是年轻一代的上进心增强了。另一个原因是社会上老人的机会增加了。然而，主要的原因可能是传统观念发生了巨大变化。
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。
74. The reasons for antisocial behavior are both complicated and varied . I suggest the phenomenon results from inappropriate role models and the lack of well-defined norms of behavior . However , the main reason is quite likely the continuing degeneration of social values .
反社会行为的原因既复杂又多样。我认为这种现象是不恰当的角色典型和缺少行为规范的很好的定义造成的。然而，主要原因很可能是不断贬低的社会价值。
75. The causes of racial hatred are not readily definable . Sociologists , however , attribute them to the misguided concept of a superior race and an innate mistrust of people
of color . Perhaps the main cause is quite simply ignorance . 种族仇恨的起因没有现成的答案。然而，社会学家把原因归结为被误导的更高贵的种族的观念以及天生的对有色人种的不信任。主要原因可能仅仅是因为无知。
76. The scourge of HIV/AIDS currently engulfing the world will quite likely be brought under control within the next few years thanks to the untiring efforts of scientists and researchers worldwide .
现在席卷世界的艾滋病的祸害很有可能由于全世界科学家和研究人员的不懈努力在未来几年内得到控制。
77. The incidence rate of cancer mainly stems from several factors , including inappropriate diets , poor healthcare practices and the lack of early detection . Continuing medical advances and rising awareness do , however , offer promising hope for the future .
癌症的发病率主要由以下诸多因素引起，包括不适当的饮食、不好的保健习惯以及没有及早发现。然而，医学的不断进步和对此不断增强的关注给未来带来了很大的希望。
78. Increased urban pollution levels and the mounting death toll from motor vehicles accidents can mainly be attributed to the glut of automobiles appearing on city roads in recent years . Detrimental factors will quite likely
outweigh the benefits of rising automobile usage . 城市人口的增长和车祸中死亡率的增加主要是由于近年内充斥城市道路的汽车。汽车使用量的增加带来的有害因素很有可能超过它的好处。
79. The rising divorce rate in China can , at least in part , be attributed to spousal incompatibility , disparities in education levels , changing social attitudes and the increasing upward mobility of the younger generation . 中国上升的离婚率可以，至少部分可以归结为婚姻的不和谐，受教育水平的差异，变化的社会看法以及年轻一代不断增强的上进心。 80. State-owned enterprises are not only failing because of inefficient management , but also because of their inability to awitch operational modes from the former planned economy to the new market economy .
国有企业失败不仅由于低效的管理，也因为他们不能实现从以前的计划经济到新的市场经济的运作模式的转换。
81. Although we do not know the long-term consequences of separation or deprivation , we do know that they can produce acute immediate distress .
虽然我们不知道分离和丧失亲人的长期后果，但我们知道它们能立即引起剧烈的悲痛。
82. One can raedily trace the disappearance of dinosaurs