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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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单选题The term diesel engine scavenging means（）A
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combustion and expansion of hot gas
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单选题"Scavenging" on a diesel engine means （）.A
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单选题Any increase in the exhaust back pressure of a four-stroke/cycle diesel engine will （）.A
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单选题In a two-stroke engine, there are always a series of openings known as （）, and in some circumstances, there are also openings known as （）, in the part of the cylinder liner.A
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单选题The timing of diesel engine air starting valves is controlled by（）A
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