程控交换设备的标称直流工作电压一般为-48V，直流电压允许变化范围是()。A:-57～-40VB:-55～-40VC:-55～-42VD:-5...

作者: rantiku 人气: - 评论: 0

问题程控交换设备的标称直流工作电压一般为-48V，直流电压允许变化范围是()。

选项 A:-57～-40V B:-55～-40V C:-55～-42V D:-53～-45V

答案 A

解析

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