1、主轴零件用几个图形表达其结构
A、3个  B、5个  C、6个  D、8个
A、A、3个
B、B、5个
C、C、6个
D、D、8个

单项选择题电枢电流相位滞后空载电动势相位90度时的电枢反应是（）

单项选择题The Pulitzer Prize is an award for achievements in newspaper, magazine, literature, and musical composition in the United States. As a jazz musician, _____________ was awarded a Pulitzer Prize for music in 1999 for writing over 1,000 compositions.