单项选择题
AC and DC generators are similar in that they （）
A.both generate alternating voltages B.both rectify the voltage before delivery C.are constructed at the same physical size for the same kilowatt rating D.both supply three-phase power
单项选择题 To increase the frequency of an operating AC generator, you should （）
单项选择题 When measuring AC current flow, you must always connect the meter （）
单项选择题 The frequency of an AC generator is adjusted by means of the （）
