31、 根據(jù)以下內(nèi)容回答31-50題：

　　Scientists know that there are two basic approaches to prolonging life(延長(zhǎng)壽命)，one approache is the elimination of the diseases that generally affect older people—diseases such as cancer，heart attack and stroke.(1)is the delay of the process of growing-old the(2)of the body.

　　In recent years scientific researchers(3)much time in the study of the process of aging.They believe that，within a few years，they will develop the knowledge and the(4)to delay the aging process for lo to 15 years.The result will be that more people will live longer，more healthful lives.At present，scientists believe that with the right diet，exercise，medical(5)，and mental attitude many people can live to he l00 years old.

　　Gerontologists(老年學(xué)專家)，people who(6)studies of the problems of growing old，are investigating(7)body cells slow down and(8)die.They feel that delaying this slowing down process(9)help postpone death.In a number of American universities，scien-tists are studying the activity of cells，the effects of diet and internal body temperature on aging.If their studies are successful，the results should help(10)the quality of life for older people in the next few years，as well as increase the life span of the next generation.

　　請(qǐng)回答(1)題

　　A.Others

　　B.Another

　　C.The other

　　D.One more