单选题Air scavenging of a diesel engine cylinder（）Ablows out the exhaust gasesBsupplies oxygen for combustionCcools the valves and cylinder wallsDall of the above
单选题
Air scavenging of a diesel engine cylinder（）
A
blows out the exhaust gases
B
supplies oxygen for combustion
C
cools the valves and cylinder walls
D
all of the above
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