Is there a limit to the number of years that a person can expect to live? Can changes in

Is there a limit to the number of years that a person can expect to live? Can changes in life-style add years to one’s life? Throughout history people have sought answers to these questions and others.
Various myths offer the hope of great longevity. In the imaginary land of Shangri-La, for example, people are said to lead a charmed existence for a thousand years. The Spanish explorer Ponce de Leon was convinced that he would find the Foundation of Youth in what is now the state of Florida. According to the Bible, Methuselah lived to be more than 900 years old.
The subject of longevity is fascinating, and scientists study individuals such as Jeanne Calment to learn about the aging process. Calment died in 1997 in Arles, France, at the age of 122. She never married, and she lived in her own apartment until moving to a retirement community when she was 109.
Most scientists agree that bodies will last, at best, about 125 years. This potential has changed little since modern human beings appeared more than 100 thousand years age. Recent improvements in medicine and the environment have extended life expectancy, especially for those from poorer parts of the world. It is not clear, however, whether such improvements will lengthen life expectancy beyond a certain point.
Life expectancy is the number of years an infant can be expected to live, given the conditions into which it is born. Life expectancy, therefore, is affected by nutrition, medical care, and social and political circumstances. An individual’s genetic makeup is also an important factor. Children from long-lived families can hope to enjoy long lives themselves. According to recent data, the average life expectancy worldwide in 1998 was 67 years. This can be compared with an average life expectancy of 77 in the United States.
In 1970 the average life expectancy worldwide was 61 years, or 6 years less than it was in 1998. This same period saw a drop in infant mortality -— the death of a child before the first birthday-—from 80 births out of 1,000 to 54 births out of 1,000. According to some researchers, the rise in the average life expectancy is due primarily to the drop in infant mortality. It is not so much that adults are living to an older age. It is, rather, that more people are living into adulthood because more children are surviving beyond their first birthdays.
【小题1】Infant mortality is defined as .A．the number of children born aliveB．the kinds of behavior typical of very young childrenC．the number of children, out of 1,000 births, who die before their first birthdayD．the typical and obvious thoughts of very young children【小题2】Although it may be possible to improve the life expectancy of a particular group of people, .A．it is more difficult to affect the rate of infant mortalityB．it is unlikely that one will be able to extend the potential life span of human beings in generalC．the process of evolution is extending the potential life span beyond 125 yearsD．the potential that bodies will last, at best, about 125 years has changed much since modern human beings appeared【小题3】One can infer that people have at times imagined that .A．people live longer in the state of FloridaB．a long life is a burden rather than a blessingC．it is possible to find a way to live for centuriesD．life expectancy is affected by a couple of factors【小题4】One can conclude that .A．the aging process can be stopped.B．the aging process is inevitable.C．life expectancy in the United States will soon reach 125 years.D．the average life expectancy worldwide is decreasingC

(答案→)C 解析：人的寿命有局限吗？改变生活方式可以延长寿命吗？自古以来，古今中外的人们都在试图破解生命之谜，寻找长寿之方。然而科学家们却认为人的寿命除了受营养、医疗、社会和政治环境影响外，人的遗传基因也起着非常重要的作用，所以人的寿命不是可以无限延长的。【小题1】C 词意猜测题。根据末段infant mortality -— the death of a child before the first birthday-—from 80 births out of 1,000 to 54 births out of 1,000.可知infant mortality指的是婴儿死亡率，故C选项正确。【小题2】B根据文章第四段内容可知人的寿命受多种因素影响，比如营养、医疗、社会和政治环境而且人的遗传基因也起着非常重要的作用，由此推断人们的寿命不可能全部延长，所以B为正确选项。【小题3】C细节理解题。根据文章第二段的内容可知人们曾认为某些地方的人们能活到将近一千年，由此可知C选项正确。【小题4】B推理判断题。根据文中Most scientists agree that bodies will last, at best, about 125 years.以及下文Life expectancy, therefore, is affected by nutrition, medical care, and social and political circumstances.可知无论怎样想方设法延长寿命，人的死亡是不可避免的，所以B选项正确。

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