2017届浙江省常山县高考英语一轮复习阅读理解专练：6（含答案）_高考复习指南

2017届浙江省常山县高考英语一轮复习阅读理解专练：6（含答案）

　　阅读下面短文，掌握其大意，从每题所给的A、B、C、D四个选项中，选出最佳选项。

　　Like distance runners on measured course, all of us will move through time in a roughly predictable pattern.

　　In the first stage of our lives, we develop and grow, reaching toward the top of physical vitality (energy).

　　After we grow up, however, the body begins a process of gradually wearing out.

　　A new awareness of physical fitness may help lengthen our years of health and vitality, yet nothing we do will work to stop the unavoidable force of aging.

　　Most of the changes of aging take place deep inside the body. The lungs become less able to take in oxygen. Powerful muscles gradually lose their strength. The heart loses power and pumps less blood. Bones grow easier to break.

　　Finally, we meet a stress, a stress that is greater than our physical resistance. Often, it is only a minor accident or chance infection (a disease caused by virus), but this time, it brings life to an end.

　　In 1932, a classic experiment nearly doubled the lifetime of rats, simply by cutting back the calories (unit for measuring the energy value of food)in their diet. The reason for the effect was then unknown.

　　Today, at the University of California at Berkley, Dr. Paul Seagle has also greatly lengthened the normal lifetime of rats. The result was achieved through a special protein (蛋白质)limited diet, which had a great effect on the chemistry of the brain. Seagle showed that within the brain, specific chemicals control many of the signals that influence aging. By changing that chemical balance, the clock of aging can be reset.