单项选择题
When measuring AC current flow, you must always connect the meter （）
A.in series with the power source and load B.in parallel with the power source and load C.insuring correct polarity D.using the lowest range possible to prevent instrument damage
单项选择题 The frequency of an AC generator is adjusted by means of the （）
单项选择题 When the current flow through a copper wire increases, its （）
单项选择题 When securing an AC generator, you should FIRST （）.
