单项选择题
A.visual inspection of the elements
B.the pressure drop across the filter
C.high lube oil sump temperature
D.decrease in oil viscosity from the filter
单项选择题 In an auxiliary boiler steam and water system, the highest pressure will be in the （）.
单项选择题 If the jacket water temperature of an operating diesel engine suddenly rises above normal, the cause can be attributed to （）.
单项选择题 The possibility of damage from operating a diesel engine at critical speeds is reduced by the use of（）.