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單項(xiàng)選擇題

An alternator is being paralleled with one on the lineAt the INSTANT the circuit breaker is closed, the frequency of the incoming alternator will normally （）.

A.increase
B.not change
C.decrease
D.be exactly 60 hertz

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單項(xiàng)選擇題

Current flowing in only one direction is called （）

A.alternating current
B.omnidirectional current
C.direct current
D.sinusoidal current

單項(xiàng)選擇題

Accidental grounds in a shipboard electrical system must be repaired as soon as possible as they will （）

A.result in immediate power outages
B.damage circuit breakers
C.appear on the ground detection system
D.damage insulation and may cause outages