单项选择题
A.Holding the valve open for a long period
B.Increasing the starting air pressure used
C.Opening the stating air valve quickly
D.Reducing the starting air valve size
单项选择题 Small crack in the crankshaft bearing surface of a diesel engine are an indication of（）
单项选择题 Fuel oil day tanks for diesel engines must be checked and cleaned and cleaned at regular intervals in order to remove（）
单项选择题 Excessively worn, or polished ends on a diesel engine valve spring, indicate（）