4．The Process of Ageing
At the age of twelve years，the human body is at its most vigorous．It has yet to reach its full size and strength，and its owner his or her full intelligence； but at this age the possibility of death is least．Earlier，we were infants and young children，and consequently more vulnerable （易受伤的）； later，we shall undergo a progressive loss of our vigour and resistance which，though vague at first，will finally become so steep that we can live no longer，however well we look after ourselves，and however well society，and our doctors，look after us．
This decline in vigour with the passing of time is called ageing．It is one of the most unpleasant discoveries which we all make that we must decline in this way，that if we escape wars，accidents and disease we shall eventually"die of old age"，and that this happens at a rate which differs little from person to person，so that there are heavy odds in favor of our dying between the ages of sixty-five and eighty．Some of us will die sooner，a few will live longer----on into a ninth or tenth decade．But the chances are against it，and there is a virtual limit on how long we can hope to remain alive，however lucky and physically strong we are．
Normal people tend to forget this process unless and until they are reminded of it．We are so familiar with the fact that man ages，that people have for years assumed that the process of losing vigour with time，of becoming more likely to die the older we get，was something self-evident，like the cooling of a hot kettle or the wearing-out of a pair of shoes．They have also assumed that all animals，and probably other organisms such as trees，or even the universe itself，must in the nature of things"wear out"．
Most animals we commonly observe do in fact age as we do，if given the chance to live long enough； and mechanical systems like a wound （上发条的） watch，or the sun，do in fact an out of energy in accordance with the second law of thermodynamics （热力学）．But these are not similar or equivalent to what happens when man ages．A run-down watch is still a watch and can be rewound．An old watch，by contrast，becomes so worn and unreliable that it eventually is not worth mending．But a watch could never repair itself-it does not consist of living parts，only of metal，which wears away by friction （摩擦）．We could，at one time，repair ourselves-well enough，at least，to overcome all but the most instantly fatal illnesses and accidents．Between twelve and eighty years we gradually lose this power，an illness which at twelve would knock us over，at eighty can knock us out，and into our grave．If we could stay as vigorous as we are at twelve，it would take about 700 years for half of us to die，and another 700 for the survivors to be reduced by half again．
74．What can be learned from this passage is thatD．
A．people usually are unhappy when they are reminded of ageing
B．children reach their full intelligence at the age of twelve years
C．people are usually more likely to die at the age of twelve years
D．our first twelve years represent the peak of human development
75．The underlined word"it"in the last sentence of Paragraph Two refers toC．
A．remaining alive until 65 B．dying before 65 or after 80
C．remaining alive after 80 D．dying between 65 and 80
76．What does"ageing"mean according to the passage？B
A．It is a fact that people cannot live any longer．
B．It refers to a gradual loss of vigor and resistance．
C．It is usually a phenomenon of dying at an old age．
D．It is a period when people are easily attacked by illness．
77．What do the examples of the watch refer to in the last paragraph？D
A．Normally people are quite familiar with the ageing process．
B．The law of thermodynamics functions in the ageing process．
C．All animals and other organisms undergo the ageing process．
D．Human's ageing process is different from that of mechanisms．
分析 本文属于说明文阅读，作者通过这篇文章主要向我们描述了"衰老"这一话题，人体生命力变化的抛物线趋势指出12岁精力最为旺盛；而人类的衰老是不可抗拒的，它与手表等机械装置的"衰老"过程完全不同．
解答 74．D．细节理解题．根据文章第二段"It has yet to reach its full size and strength，and its owner his or her full intelligence； but at this age the possibility of death is least"人的体型和力量变得充沛，智力上升；在这个年龄死亡的可能性最小，可知十二年是人类发展的高峰；故选D．
75．C．词义推断题．根据文章第二段"Some of us will die sooner，a few will live longer----on into a ninth or tenth decade"有些人逝去的早，而少数人可以活到85到95岁，可知下文为我们所期望的寿命实际上是有限的，因此it应该代指长寿；故选C．
76．B．细节理解题．根据文章第二段"This decline in vigour with the passing of time is called ageing"这种随着时间的流逝精力衰退的现象称为老化，故选B．
77．D．推理判断题．根据文章第四段"But a watch could never repair itself-it does not consist of living parts，only of metal，which wears away by friction （摩擦）．We could，at one time，repair ourselves-well enough"手表不能像人类的身体那样进行自我修复，而人类的自我修复还可以在一定程度上缓解病痛、延长生命，可知这就表明人类和手表等机械装置的"衰老"过程有较大的区别，是不同的衰老机制；故选D．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
