无码高清视频|成人自拍视频|欧美成人午夜无码A片秀色直播|草美女视频网站|美女被操网站在线观看

單項(xiàng)選擇題

As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to ().

A.draw a one line diagram of the circuitry
B.test all fuses and measure the line voltage
C.take megger readings
D.insulate the apparatus from ground

微信掃碼免費(fèi)搜題