单项选择题
The frequency of an AC generator is controlled by the （）
A.rheostat B.governor C.exciter D.capacitor
单项选择题 Capacitance is the property of an electric circuit opposing a change in the （）
单项选择题 Inductance is the property of an electric circuit that （）
单项选择题 The operator of electrical motors should keep a constant check on the loads they carry because （）
