单项选择题
A.opposite polarity B.the same polarity C.negative polarity D.positive polarity
An a-cswitchboard is usually（） the corresponding d-cboa...
单项选择题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
The star formation is most commonly used and requires（）...
单项选择题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
The field coils（） and the armature is（）This is in fact ...
单项选择题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
