单项选择题
A.dischargeendbeingsmallerthanthesuctionend
B.smallsizeofimpeller
C.lackofmovingparts
D.easeatwhichthewearingringsmaybechanged
单项选择题 The heat required to change a substance from a liquid to a gas without experiencing a temperature change is defined as the latent heat of ().
单项选择题 Which of the processes listed consumes the greatest amount of power while producing the greatest amount of heat?()
单项选择题 The degree to which the viscosity of an oil will change with a change in temperature is indicated by the ().