[简答题]

The Development of Television Technology

Radio and television were major agents of social change in the 20th century. Radio was once the center for family entertainment and news. Television enhanced this revolution by adding sight to sound. Both opened the windows to other lives, to remote areas of the world, and to history in the making. News coverage changed from early and late editions of newspapers to broadcast coverage from the scene. Play-by-play sports broadcasts and live concerts enhanced entertainment coverage. For many, the only cultural performances or sports events they would ever hear or see would emanate from the speakers or the screens in their living rooms. Each has engaged millions of people in the major historical events that have shaped the world.
If people could look at the sky and see how it is organized into frequency bands used for different purposes, they would be amazed. Radio waves crisscross the atmosph

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