OSI参考模型中定义了很多层次，各个层次之间的数据交换是通过（）来实现的。

听力原文： Not everybody reads the daily newspaper. People who do not read newspapers are sometimes referred to as nonreaders. Early research has shown that nonreaders are generally low in education, low in income, either very young or very old. In addition, nonreaders are more likely to live in rural areas and have less contact with neighbors and friends. Other studies show that nonreaders tend to isolated themselves from the community, are less likely to own a home and seldom belong to local voluntary organizations. Why don't these people read the daily paper? They say they don't have the time; they prefer radio or TV; they have no interest in reading at all. And besides, they think newspapers are too expensive. Recent surveys, however, have indicated that the portrait of the nonreader is more complicated than first thought. There appears to be a group of nonreaders that does not fit the type mentioned above. They are high in income, and fall into the age group of 2665. They axe far more likely to report that they don't have the time to read the papers and they have no interest in the content. Editors and publishers axe attempting to win them back. First, they are adding news briefs and comprehensive indexes. This will help overcome the time problem. And they are also giving variety to newspaper content to help build the readers' interest.(26)A．They are interested in other kinds of reading.B．They are active in voluntary services.C．They tend to be low in education and in income.D．They live in isolated areas.

A.
(26)
A．They
B.
B．They
C.
C．They
D.
D．They
E.

点击查看答案

A．Fellow teachers.B．Freshmen of a university.C．Secondyear students.D．Either seniors or juniors.

A.Fellow
B.
B．Freshmen
C.
C．Secondyear
D.
D．Either
E.

点击查看答案