单元整体教案NSEFCII-U02(The first period)

概要： many hundreds of radio stations broadcasting in different languages and in all countries. The invisible radio waves can easily travel from one country to another. This means that listeners in one country can listen to programmes broadcast from another country. In this way information travels from country to country. Radio is often used by policemen to communicate with one another. In addition,

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            many hundreds of radio stations broadcasting in different languages
            and in all countries. The invisible radio waves can easily travel
            from one country to another. This means that listeners in one
            country can listen to programmes broadcast from another country. In
            this way information travels from country to country. Radio is often
            used by policemen to communicate with one another. In addition,
            police forces in one country can communicate with those in other
            countries in order to catch criminals. Ships at sea use radio so
            that they know exactly where they are. Aeroplanes use radio for the
            same reason and this makes it easier for them to find their way from
            place to place.
            In the modern world there are many methods of communication. As well
            as radio there is television, for example. This enables information
            in the form of a picture to be broadcast from one place to another.
            Radio is often used as part of a telegraph system where distances
            are very large. Of the many modern methods of communication, radio
            probably remains the most important.
            2. How the Program Is Broadcast?
                We turn on the radio and a program comes to us from a
            broadcasting station miles and miles away. We know that words and
            music themselves haven’t traveled all that distance through space,
            but something certainly is bringing the program from the station.
            What is this silent carrier?
                The answer is radio waves. We can not see radio waves or feel
            them or even hear them. In fact, nobody knows exactly what they are.
            But we do know that they are made by electricity, and we have
            learned how to use them.
            At the broadcasting station people talk or sing, instruments (乐器)

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