单项选择题
A signal derived from a controlled function and returned to the initiating point is called a/an （）.
A.monitoring signal B.inverse signal C.reverse signal D.feedback signal
单项选择题 The purpose of a main switchboard circuit breakers reverse-power trip is to （）.
单项选择题 When you are making a high potential test on a piece of repaired electrical machinery, a rise in leakage current indicates （）.
单项选择题 The sub-multiple prefix "milli" (m) means （）.
