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单元整体教案NSEFCII-U2017(The first period),
travel long distances along wires. Instead invisible waves, moving
at the same speed as electrical signals, are used. A few years ago
there were not many radio stations in the world. Today there are
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.
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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)
play, doors slam(砰) ,and all of these make sound waves. The sound
waves reach the microphone, and here they are changed into
electricity. Then from a tall tower called the broadcasting aerial
(天线) ,electricity sends radio waves. The waves travel in every
direction, and some of them reach our radio aerial. Now a wonderful
thing happens. The radio waves start an electricity current (电流) in
our aerial like the one that was first made in the broadcasting
station. Finally, the loudspeaker in our set changes electricity
into sound, and we hear the program.
The First Period
Teaching Aims:
1. Learn and master the following words and phrases:
media, reliable, fire, face, difficulty, elect, go up, burn down,
injure
2. Practise expressing opinion using the following:
What do you think of…?
What's your opinion?
Why do you choose…?
Perhaps…is more important.
I would rather choose.…
I don't think we should choose…
Maybe it would be better to choose…
Our readers want to know about…
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