单项选择题
A.oil foaming will occur
B.large quantities of oil are consumed
C.lube oil viscosity is always decreased
D.corrosive by-products are usually formed
单项选择题 When disassembling or assembling an injection pump plunger and barrel you should （）
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 （）