The making of glass is a very old industry at least 4,500 years old. Glass has many extraordinary qualities and it is frequently being used in new ways.

One of the most interesting new uses for glass is in telephone communication. Scientists have developed glass fibers as thin as human hair which are designed to carry light signals. When the light reaches the other end, it is first changed into electrical signals, which are in turn converted into sound messages.

Called light wave communication, the new system was used successfully in an experiment in Chicago in 1977. During the experiment, two glass fibers were able to carry. 672 conversations at the same time. The light wave cable, containmg 144 glass fibers, has the capacity to carry 50,000 conversations at the same time.

The light wave communication system has two important advantages. First, the glass fiber cables are smaller and weigh less than copper cables. Second, they cost less,
Perhaps it can be said that telephone communication has entered the age of light!

單選題?One of the extraordinary qualities of glass is that it can carry ______.

• A、?sound signals

• B、?light signals

• C、?electrical signals

• D、?any signal

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單選題?Before you can hear a message on the telephone using the new system, ______.

• A、?electrical signals must first be changed into light signals and then into sound

• B、?the light signals have to be changed directly into sound messages

• C、?light must first be changed into electrical signals and then into sound

• D、?either the light or the electrical signals have to be changed into sound message

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單選題?According to the passage the new telephone communication system ______.

• A、?had been used within limited scope before 1977

• B、?was first put into actual use in 1977

• C、?had been repeatedly experimented on before 1977

• D、?was put on experiment in 1977

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單選題?From the passage, you can tell that people prefer glass fiber cables to copper cables because ______.

• A、?glass fibers are less expensive

• B、?glass fibers deliver messages directly

• C、?glass fibers are more up to date

• D、?glass fiber are easier to make

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單選題?Which of the following statements best expresses the main idea of the passage?

• A、?Glass is very useful because it has many unusual qualities.

• B、?Light signals have changed the use of glass in industry.

• C、?Glass fibers have reduced the cost of telephone communication.

• D、?The use of glass fibers to carry telephone messages is an interesting new development.

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