单项选择题
A.generate its own electrical power
B.transform electrical energy into mechanical energy
C.increase or decrease circuit voltage as required
D.convert AC current to DC current
单项选择题 When placed in a magnetic field, which of the materials listed will maintain the highest permeability?（）
单项选择题 An ohmmeter can be used to measure（）
单项选择题 The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage （）.