单项选择题
A.a glazed surface on the spring
B.nicks in the protective coating
C.a build up of sludge deposits
D.cracks in the surface of the spring
单项选择题 Which of the routine maintenance procedure listed is required for starting air receivers?（）
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 （）