單項選擇題A semiconductor is a material with a （）.

A.conductivity higher than a normal conductor
B.conductivity higher than a normal insulator
C.high conductivity at low temperatures
D.low conductivity at high temperatures


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1.單項選擇題The sub-multiple prefix “micro” means （）.

A.thousandth (10 to the-3rd power)
B.millionth (10 to the-6th power)
C.billionth (10 to the-9th power)
D.trillionth (10 to the-12th power)

2.單項選擇題A signal derived from a controlled function and returned to the initiating point is called a/an （）.

A.monitoring signal
B.inverse signal
C.reverse signal
D.feedback signal

3.單項選擇題The purpose of a main switchboard circuit breakers reverse-power trip is to （）.

A.prevent main circuit overload
B.protect the circuit breaker blowout coil
C.prevent alternator motorization
D.prevent low voltage tripout

4.單項選擇題When you are making a high potential test on a piece of repaired electrical machinery, a rise in leakage current indicates （）.

A.good insulation
B.bad insulation
C.high insulation power factor
D.a high slot discharge factor

5.單項選擇題The sub-multiple prefix "milli" (m) means （）.

A.one thousandth (10 to the -3rd power)
B.one millionth ( 10 to the -6th power)
C.one billionth ( 10 to the -9th power)
D.one trillionth (10 to the -12th power)