单项选择题
Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to（）
A.facilitate bi-directional operation
B.provide the greatest pump efficiency
C.prevent pump clogging from marine growth
D.prevent cavitation at the pump outlet
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相关考题
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单项选择题
In a diesel engine cooling system, the high temperature alarm contact maker will be activated on excessively high water discharge temperature from the （）
A.raw water pump discharge
B.expansion tank outlet
C.cooling water heat exchanger
D.outlet engine jacket water outlet -
单项选择题
In a diesel engine, a cylinder liner should be replaced if it is （） Ⅰ.Scuffed Ⅱ.Scored
A.Ⅰ only is correct
B.Ⅱ only is correct
C.both Ⅰ and Ⅱ are correct
D.neither Ⅰ or Ⅱ are correct -
单项选择题
Under normal conditions, the main source of crankcase oil contamination is attributed to （）
A.metal particles loosened by wear
B.air when air cleaners are not used
C.condensation of water vapors
D.breakdown of the lubricating oil by dilution
