單項(xiàng)選擇題Copper is often used as an electrical conductor because it ().

A.has high resistance at low temperatures
B.has a highly polished surface
C.is able to pass current with little opposition
D.holds insulation together well


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1.單項(xiàng)選擇題A device which prints out a permanent record of the plant operating conditions is known as the ().

A.analogger
B.bell logger
C.alarm logger
D.data logger

2.單項(xiàng)選擇題Which of the following types of motors is often designed for use in correcting power factor?()

A.Polyphase
B.Wound-rotor
C.Induction
D.Synchronous

3.單項(xiàng)選擇題Power transformers are rated in ().

A.kilowatts
B.ampere-turns
C.kilowatt-volts
D.kilovolt-amperes

4.單項(xiàng)選擇題The purpose of DC generator brushes is to ().

A.neutralize armature reaction
B.conduct electric current to an outside circuit
C.convert DC current to AC current
D.provide excitation to a DC generator

5.單項(xiàng)選擇題Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?()

A.Open the machine on both ends so as to allow the air and dust to escape
B.Be certain that the circuit breaker is opened and tagged on the feeder panel
C.Be certain that the air is clean and as dry as possible
D.All of the above