單項選擇題An a-cswitchboard is usually（） the corresponding d-cboard because of the higher voltage and lower currents and smaller bus-bars.

A.larger and heavier than
B.as much as
C.smaller and lighter than
D.more dangerous than


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1.單項選擇題The star formation is most commonly used and requires（） on the alternator.

A.one slip-ring
B.two sliprings
C.three sliprings
D.four sliprings

2.單項選擇題The field coils（） and the armature is（）This is in fact the arrangement adopted for large, heavy duty alternators.

A.stationary；rotate
B.stationary；stationary
C.rotate；stationary
D.rotate；rotate

4.單項選擇題With a purely resistance load the voltage and current are in phase, giving a power factor of （）.

A.one
B.less than one
C.more than one
D.negative one