单项选择题
Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）
A.during the valve overlap period B.with only the exhaust valve open C.at a pressure below atmospheric D.without cooling the cylinders or pistons
单项选择题 A diesel engine piston crown can crack from （）
单项选择题 Fuel oil contamination of an auxiliary diesel engine lube oil can result in（）
单项选择题 When a fuel injection nozzle overheats, which of the problems listed can be expected?（）
