听力原文：Television or TV is a modem wonder of electronics. It brings the world into our o

听力原文： Television or TV is a modem wonder of electronics. It brings the world into our own home in sight and sound. Experiments leading to modem television took place more than a hundred years ago. By the 1920s, inventors and researcher had turned the early theories into working models. Yet it took another thirty years for TV to become an industry.

As an industry, TV provides jobs for hundreds of thousands who make TV sets and broadcasting equipment. It also provides work for actors, technicians, and others who put on programs. As an art, television brings the theatre and other cultural events into the home. Its influence on the life of average people is incalculable: it can influence their thoughts, their likes and dislikes, their speech, and even their dress. It can also add to their store of knowledge. Through advertising, television helps businesses and manufacturers sell their products to millions of persons. Television has brought political campaigns closer to the voters than in former days. Educational TV stations offer teaching in various subjects ranging from home nursing to art appreciation. Many large schools and universities have closed-circuit television equipment that will telecast lectures and demonstrations to hundreds of students in different classrooms, and the lecture can be put on video tape to be kept for later use. Some hospitals use TV to allow medical students to get close-up views of operations.

The programs that people watch are not only local and national ones. Since the launching of the first communication satellite, more and more programs are televised "live" from all over the world. Television viewers in San Francisco were able to watch the Olympic Games in Tokyo by means of a communication satellite named Syncom. And live telecasts now come from outer space: In 1969, the first astronauts landing on the moon televised their historic "moon walk" to viewers on the earth. Since then, astronauts have regularly sent telecasts to the earth.

It looks as if the uses of television in education, entertainment and communication appear to be endless. TV is certainly one of the major modem wonders of electronics in our changing world.

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A．by the 1920s

B．by the 1950s

C．by the 1910s

D．by the 1930s

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