单项选择题
A.0.5MΩ;1MΩ B.1MΩ;1MΩ C.1MΩ;0.5MΩ D.0.5MΩ;0.5MΩ
A.导轨架 B.附墙架 C.钢丝绳 D.钢管
A.4/1000 B.3/1000 C.2/1000 D.1/1000