[单项选择]What social scientists have long felt puzzled about
A. The mortality rate can not be predicted.
B. The death toll remained stable year after year.
C. A quota for each type of death has not come into being.
D. People lost their lives every year for this or that reason.

[单项选择]What social scientists have long felt puzzled about is why ______.
A. the mortality rate can not be predicted
B. the death toll remained stable year after year
C. a quota for each type of death has not come into being
D. people lost their lives every year for this or that reason

[单项选择]The social scientists have long felt confused about the fact that______.
A. 2,500 people accidentally commit suicide every year
B. the death rates remained stable year after year
C. a quota for each type of death has not established
D. people lost their lives every year for this or that reason

[单项选择]Sociologists have long recognized that social tensions are elements of group life.
A. average
B. routine
C. normal
D. standard

[单项选择]John ______ from social activity because he felt embarrassed with people.
A. held on
B. held back
C. held off
D. held out

[单项选择]Social scientists have recently become greatly interested in space because ______.
A. space industrialization will create new markets and more jobs on Earth
B. space exploration will be harmful to man
C. space colonization is near at hand
D. otherwise technologists will catch the opportunity to go to space

[单项选择]

Text 3
Lately social scientists have begun to ask if culture is found just in humans, or if some animals have culture too. When we speak of culture, we mean a way of life a group of people have in common Culture includes the beliefs and attitudes we learn. It is the patterns of behavior that help people to live together. It is also the patterns of behavior that make one group of people different from another group.
Our culture lets us make up for having lost our strength, claws, long teeth, and other defenses. Instead, We use tools, cooperate with one another, and communicate in language. But these aspects of human behavior, or "culture", can also be found in the lives of certain animals.
We used to think that the ability to use tools was the dividing line between human beings and other animals. Lately, however, we have found that this is not the case. Chimpanzees can not only use tools but actually make tools themselves. This is a major s
A. the history of animal learning
B. the difference between animals' culture and that of human beings
C. the various aspects of animals culture
D. the dividing line between animals and human beings