人在炎热环境进行体力活动时,动—静脉短路常处于()。
查看答案
空调工况下制冷剂的蒸发温度为()℃,冷凝温度为()℃。
Which of the listed conditions can lead to cavitation气穴in a centrifugal pump?()
A. Vapor pockets formed in the suction flow stream
B. Rough easing volute surfaces
C. Worn wearing rings
D. Heavy fluid in the flow stream
气体在流动过程中与管壁会发生摩擦,产生(),所以要接地装置。
A. 摩擦
B. 静电
C. 阻力