LBJ馈线衰耗不大于()。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
当有线电视系统传输干线的衰耗(以最高工作频率下的衰耗值为准)大于100dB时,可采用下列哪些传输方式?( )
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