【判断题】三相感应电动机的起动电流很大,所以其起动转矩也很大。
【单选题】债券分为实物债券、凭证式债券和记帐式债券的依据是( )。
【多选题】开关的顶盖部分由滑板、 、扭簧和手柄等构成操作机构,机构由 储能,可使触点快速分断或闭合,保证开关在切断负荷 时,迅速熄灭电弧。触点分断或闭合的速度,与手柄旋转的 无关。
【单选题】In the US school systems, which of the following divisions is true?
A.
Elementary school, grammar school.
B.
Elementary school, junior high school.
C.
elementary school, secondary school.
D.
Junior high school, senior high school.