单项选择题
An efficient seal between the cylinder block and cylinder heads on many diesel engines is obtained with（）
A.graphite packing B.sealing compound C.lubricating oil D.gaskets
单项选择题 What is the function of the after-cooler installed in the diesel engine air intakes system?（）
单项选择题 Which harmful consequence may be the result of lube oil sludge accumulation? （）
单项选择题 High cylinder firing pressure, accompanied by low exhaust temperature, can result from （）
