【单选题】在电动机起动或短时过载时,热继电器不会动作,这可避免电动机的不必要停车,这种“热惯性”使热继电器不能做( )保护。
【简答题】During last summer vocation, I decided to find a part-time job. During last summer vocation, I decided that ______.
【单选题】泵在工作时下述五种原因造成了能量损失,试判断分别属子那类损失:泵内高压油通过缝隙流到低压油。()
【简答题】During last summer vocation, I decided to find a part-lime job. During last summer vocation, I decided that ______ .
【多选题】下列关于液压泵的分类正确的是()
C.
按泵的输入的流量能否调节可分为定量泵和变量泵
D.
按泵的额定压力的高低可分为低压泵、中压泵和高压泵
【单选题】人们常按液压泵额定压力的大小来进行分类,柱塞泵属于( )油泵。
【单选题】I_____at a summer camp in New York last summer and enjoyed supervising a group of four children.
【单选题】I suggest that we _____ to the Summer Palace tomorrow.
A.
I suggest that we ________ to the Summer Palace tomorrow.
【单选题】下列关于热继电器的介绍不正确的是( )
B.
热继电器还可以实现断相保护和电流不平衡运行保护
D.
热继电气的95/96是一组常闭触头,使用是不必在检测