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 ageing 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 ageing 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 without intellectual or emotional faculties.)
　　Contraction of front and side parts—as cells die off—was observed I 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 findings 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.”
36. The team of doctors wanted to find out ________.
　　A. why certain people age sooner than others   B. how to make people live longer
　　C. the size of certain people’s brains          D. which people are most intelligent
37. On what are their research findings based?
　　A. A survey of farmers in northern Japan.      B. Tests performed on a thousand old people.
　　C. The study of brain volumes of different people  D. The latest development of computer technology.
38. The doctor’s test 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 the better brains than thirty-year-olds
　　D. some people’s brains have contracted more than other people’s.
39. The word “subjects” in Paragraph 5 means ________.
　　A. something to be considered               B. branches of knowledge studied
　　C. persons chosen to be studied in an experiment
　　D. any member of a state except the supreme ruler.
40. According to the passage, which people seem to age slower than the others?
　　A. Lawyers.          B. Farmers.         C. Clerks.         D. Shop assistants.

_____ with the size of the whole earth，the biggest ocean doesn’t seem big at all．

　A．Compare B.When comparing 　C．Comparing D．When compared

When it comes to social behaviour，mammals are in a league of their own.Some birds may form pairs，or even cooperate to hunt，but the complexity (复杂性) of their relationships can hardly compare to those within a school of dolphins，a herd of elephants or a group of humans.What makes mammalian social groups different from a flock of starlings or a shoal of fish，is that in many cases the individuals could recognize each other.Although we may think that? all elephants look pretty much the same，we can easily tell individuals of our own species apart and it has become clear through studies that the same is true of other species.Dolphins have their own signature whistles that act like “names”，and elephants can recognize and greet other individuals they have known but not seen for many years.This is something that only a few species of birds appear to be able to do.

Mammals in complex social groups not only recognize each other as individuals，but also they remember a lot of information about that individual.Social groups often rely on this memory—such as knowing who is dominant to whom，who is related to whom，and who has done what to whom in the past.It’s like remembering who you have lent money to or done a favour for，and who hasn’t repaid that money or has talked about you behind your back.You have to learn who to trust，who your friends are，and who to watch out for.

All this remembering goes on in a particular part of the brain called the neocortex (大脑皮层)．If you compare the size of a mammal’s social group with the size of this part of the brain，you will find they are remarkably closely related.This area seems to take a long time to develop fully and animals in which it is very large take a very? long time to grow up to adulthood.During this time，the youngster has to learn all the rules of social behaviour in their group and to piece together all? the relationships between the group members：Knowledge that will be needed to avoid getting into trouble.

1.What is special about a mammalian social group according to the passage?

A．All the individuals cooperate to hunt.

B．The individuals can communicate with each other.

C．The individuals can recognize each other.

D．The individuals form closer relationship.

2.The passage suggests that elephants________.

A．are cleverer than dolphins

B．can recognize other species

C．may mistake a member for another

D．have good memories

3. Animals whose area of the neocortex is large________.

A．will have a long period of time before they become adults

B．will spend a shorter time learning the necessary knowledge

C．will learn the necessary knowledge much more easily

D．will have more difficulty in growing up as adults

4. If the neocortex is larger，the animals________.

A．can live a longer life

B．have a smaller social group

C．have a larger social group

D．have a greater body size

________with the size of the whole earth, the highest mountain doesn't seem high at all.

A. When compared                   B. To compare

C. While comparing                 D. It compared

__________ with the size of the whole earth，the highest mountain doesn’t seem high at all.

A.When compared                              B.To compare?

C.While comparing                                   D.It compared?