单项选择题

The resistance of electric wire will decrease as its （）

A.length increases
B.cross-sectional area increases
C.temperature increases
D.percent of metallic purities increases

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The total power consumed in a parallel circuit is （）

A.the sum of the powers used in each load (resistor)
B.divided by the number of loads
C.always less than the power used in the smallest load
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A.series with a circuit
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The primary function of an electric motor is to （）

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