单项选择题
An ammeter should be used to measure （）
A.the voltage between two points in a circuit B.circuit continuity C.current flow in a circuit D.total or partial circuit resistance
单项选择题 When the voltage remains constant and the resistance is increased in a series circuit, the flow of current （）
单项选择题 The power factor of an AC generator operating singularly is determined by the （）
单项选择题 The resistance of electric wire will decrease as its （）
