单项选择题
A.keep the parts immersed in diesel fuel
B.always keep the plunger and barrel together
C.work over a linoleum-type surface
D.all of the above
单项选择题 In an internal combustion engine, which of the devices listed will force the compression rings to seal the compression gases in the space above the piston?（）
单项选择题 If the detergent type lubricating oil being used in a diesel engine is black, the oil （）
单项选择题 Which of the following statements describes the results of excessive microbiological growths within a fuel system?（）