Directions: Read the passage carefully. Then answer the questions or complete the statements in the fewest possible words.
While contact between adolescents (between the ages of fifteen and nineteen) and their peers (同龄人) is a universal characteristic of all cultures, the nature and the degree of such contact vary a great deal. In American contemporary society, adolescents spend much more time with their peers than with younger children or adults.
This pattern of age segregation(隔离) in American society did not become usual until the beginning of the industrialized society. Changes in the workplace separated children from adults, with adults working and children attending school. The dramatic increase of mothers in the workplace has further contributed to the reduction in the amount of time adolescents spend with adults. School reform efforts during the nineteenth century, which resulted in age-segregated schools and grades, have reduced the amount of time adolescents spend with younger children. Finally, the changes in population are considered a factor that may have contributed to the emergence of adolescent peer culture. From 1955 t0 1975, the adolescent population increased dramatically, from 11 percent t0 20.9 percent. This increase in the number of adolescents might be a contributing factor to the increase in adolescent peer culture in terms of growth in size.
Research supports the view that adolescents spend a great deal of time with their peers. Reed Larson and his colleagues examined adolescents' daily activities and found that they spend more time talking to their friends than engaging in any other activity. In a typical week, high school students will spend twice as much time with their peers as with adults. This gradual withdrawal from adults begins in early adolescence. In sixth grade, adults (excluding parents) account for only 25 percent of adolescent social networks. Another important characteristic of  adolescent peer culture is its increasingly autonomous (白治的) function. While childhood peer groups are conducted under the close supervision of parents, adolescent peer groups typically make an effort to escape adult supervision and usually succeed in doing so.
(Note: Answer the questions or complete the statements in NO MORE THAN EIGHT WORDS.)
"This pattern of age segregation" refers to the phenomenon that adolescents segregate themselves from         
Besides changes in the workplace,             are the other two factors contributing to adolescent peer culture.
When do adolescents start to spend less time with adults?
How do adolescent peer groups differ from childhood peer groups?