单项选择题
A.has continuously for a long period B.suction pressure is below normal C.oil level is below normal D.starts after a long idle period
Strainers are commonly used in hydraulic systems to （）....
单项选择题Strainers are commonly used in hydraulic systems to （）.
A.protect the pump from fine soluble contaminants B.prevent solid particles from entering the pump C.prevent solid particles from entering the filter D.protect the directional control valves
On which of the following heated surfaces of a flash ty...
单项选择题On which of the following heated surfaces of a flash type evaporator would you be more likely to find soft scale formation?（）
A.Feed-water heater internal tube surfaces B.Internal distillate cooler tubes C.Flash chamber vertical surfaces D.Distilling condenser tubes
Machinery operating features are designed to help conse...
单项选择题Machinery operating features are designed to help conserve energy.Which of the following results will not contribute to energy conservation?（）
A.Reduction of friction B.Insulation of hot surfaces C.Lubrication of moving parts D.Elevation of cooler outlet temperatures
