【多选题】【消耗次数：1】
掘进工作面的局部通风机应采用“三专两闭锁”，双风机双电源自动切换。“三专”是指（ ）
①
A.专用变压器
②
B.专用开关
③
C.专用电源
④
D.专用线路
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相关题目
【单选题】
下列关于专用线路与交换线路的描述错误的是（ ）。
①
专用线路适用于数据量大的情况
②
专用线路不需要有呼叫建立与拆除过程
③
交换线路适用于数据量大的情况
④
交换线路通过交换网连接
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