【单选题】

The mass media is a big part of our culture, yet it can also be a helper, adviser and teacher to our young generation. The mass media affects the lives of our young by acting as a (an) (1) for a number of institutions and social contacts. In this way, it (2) a variety of functions in human life.

The time spent in front of the television screen is usually at the (3) of leisure: there is less time for games, amusement and rest. (4) by what is happening on the screen, children not only imitate what they see but directly (5) themselves with different characters.Americans have been concerned about the (6) of violence in the media and its (7) harm to children and adolescents for at least forty years.During this period, new media (8) , such as video games, cable television, music videos, and the Internet.As they continue to gain popularity, these media, (9) television, (10) public concern and research attention.
Another large societal concern on our young generation (11) by the media, is body image. (12) forces can influence body image positively or negatively. (13) one, societaland cultural norms and mass media marketing (14) our concepts of beauty. In the mass media, the images of (15) beauty fill magazines and newspapers, (16) from our televisions and entertain us (17) the movies.Even in advertising, the mass media (18) on accepted cultural values of thinness and fitness for commercial gain. Young adults are presented with a (19)defined standard of attractiveness, a(n) (20) that carries unrealistic physical expectations.
[A] over [B] with[C] on[D] at