单项选择题
A.larger and heavier than
B.as much as
C.smaller and lighter than
D.more dangerous than
单项选择题 The star formation is most commonly used and requires（） on the alternator.
单项选择题 The field coils（） and the armature is（）This is in fact the arrangement adopted for large, heavy duty alternators.
单项选择题 The power factor is a measure of the phase difference between voltage and current and is expressed as the（） of the phase angle.