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Sound is a form of wave energy that can travel through air.
声音其实就是声波，能在空气中行进的声波。
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Travel Wave Tube is the one of core part of transmitter in radar.
行波管是雷达发射机中的核心部件之一。
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Travel Wave Tube is the one of core part of transmitter in radar.
行波管是雷达发射机中的核心部件之一。
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