99色精品-9色在线-99色在线-99色视频 国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

單項選擇題

Sludge formation in a diesel engine lube oil system is caused by()

A.carbonization of oils from the combustion chambers
B.emulsions of lube oil and water
C.coagulation of unburned fuel below the piston rings
D.all of the above

微信掃碼免費搜題