单项选择题
A.determine the need for filter cleaning
B.measure any change in oil viscosity
C.prevent damage to the filter
D.determine the need for batch filtration
单项选择题 Which of the following statements concerning the lubrication of diesel propulsion engines used in vessels over 300 gross tons is most accurate?（）
单项选择题 If the coolant temperature of a closed cooling water system for a diesel engine gradually increases, the trouble usually is （）
单项选择题 The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）