单项选择题
A.a modern diesel engine；a turbine wheel
B.a modem diesel engine；exhaust gases
C.a compressor；an exhaust gas turbocharger
D.a compressor；a turbine wheel
单项选择题 Gas exchange, which is a basic part of the cycle of an internal combustion engine, is（）
单项选择题 “The use of a poor quality oil can lead to rapid deterioration of its properties with the resultant formation of deposits in the piston crown which in turn results in a considerable reduction in heat transfer with subsequent overheating and thermal cracking” According to this sentence, we can know that the principle reason of the overheating and thermal cracking is（）
单项选择题 Large crosshead type engine generally has two lubrication systems, a function performed only by crankcase oil system is（）