大学英语四级阅读理解练习 五

　　Questions 16 to 20 are based on the following passage:
　　If you want to stay young, sit down and have a good think. This is the research finding of a team of Japanese doctors, who say that most of our brains are not getting enough exercise-and as a result, we are aging unnecessarily soon.
　　Professor Taiju Matsuzawa wanted to find out why otherwise healthy farmers in northern Japan appeared to be losing their ability to think and reason at a relatively early age, and how the process of aging could be slowed down.
　　With a team of colleagues at Tokyo National University, he set about measuring brain volumes of a thousand people of different ages and varying occupations.
　　Computer technology enabled the researchers to obtain precise measurements of the volume of the front and side sections of the brain, which relate to intellect（智能）and emotion, and determine the human character. (The rear section of the brain, which controls functions like eating and breathing, does not contract with age, and one can continue living wihtout intellectual or emotional faculties or functions.)
　　Contraction of front and side parts-as cells die off-was observed in some subjects in their thirties, but it was still not evident in some sixty- and seventy-year-olds.
　　Matsuzawa concluded from his tests that there is a simple remedy to the contraction normally associated with age-using the head.
　　The findings show in general terms that contraction of the brain begins sooner in people in the country than in the towns. Those least at risk, says Matsuzawa, are lawyers, followed by university professors and doctors, white collar workers doing routine work in government offices are, however, as likely to have shrinking brains as the farm worker, bus driver and shop assistant.
　　Matsuzawa's fingings show that thinking can prevent the brain from shrinking. Blood must circulate properly in the head to supply the fresh oxygen the brain cells need. "The best way to maintain good blood circulation is through using the brain," he says. "Think hard and engage in conversation. Don't rely on pocket calculators."
　　16.The team of doctors wanted to find out ________.
　　 A) why certain people are aging sooner than others
　　 B) how to make people live longer
　　 C) the size of certain people's brains
　　 D) which people are most intelligent
　　17.On what are their research findings based?
　　 A) A survey of farmers in northern Japan.
　　 B) Tests performed on a thousand old people.
　　 C) study of brain volumes of different people.
　　 D）The latest development of computer technology.
　　18.The doctor's tests show that ________.
　　 A) our brains shrink as we grow older
　　 B) the front section of the brain does not shrink
　　 C) sixty-year-olds have better brains than thirty-year-olds
　　 D) some people's brains have contracted more than other people's
　　19.The word "subjects" in paragraph five means ________.
　　 A) a team of colleagues of Professor Taiju Matsuzawa's at Tokyo National University
　　 B) persons chosen to be studied in a medical experiment
　　 C) doctors and nurses in the hospital
　　 D) patients in the hospital
　　20.According to the passage, which people seem to age slower than the others?
　　 A) Lawyers.
　　 B) Farmers.
　　 C) Clerks.
　　 D) Shop assistants.