单项选择题
A.充电 B.放电 C.接地 D.接零
A.15S B.30S C.60S D.90S
A.外壳接“E”,线芯接“L”,屏蔽层接“G” B.外壳接“L”,线芯接“E”,屏蔽层接“G” C.外壳接“G”,线芯接“E”,屏蔽层接“L” D.外壳接“G”,线芯接“L”,屏蔽层接“E”