单项选择题
A.Frequent draining of accumulated moisture
B.Frequent testing of relief valves
C.A close watch on temperature to prevent fluctuations in pressure
D.Frequent cleaning to re move oil and foreign matter
单项选择题 Which of the routine maintenance procedures listed is required for starting air receivers?（）
单项选择题 A large two-stroke/cycle direct reversing diesel engine is to be reversedPrior to the admission of starting air you must （）
单项选择题 Which of the listed conditions can cause lacquer to be deposited on a piston skirt?（）