A. 零 B. 25~30% C. 铭牌效率的30% D. 空载电流与额定电流之比
A. 铂 B. 铯 C. 锑 D. 硒
A. 订货点 B. 订货周期 C. 运输方式
As long as B. As far as C. As well as D. Unle