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单选题
The power factor is a measure of the phase difference between voltage and current and is expressed as the（） of the phase angle.
A
sine
B
cosine
C
tangent
D
cotangent
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resistanceC
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Field excitation losses are kept to a minimumC
Generator rotors will have a lesser tendency to huntD
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单选题When current and voltage reach maximum values at the same time, the power factor is（）A
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