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单选题
In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressure
A
Ⅰonly
B
Ⅱonly
C
bothⅠand Ⅱ
D
neitherⅠnor Ⅱ
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after TDCB
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the proper back pressureB
the cooling water temperatureC
correct timing and proper seatingD
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late ignitionB
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单选题What is the purpose of the intake/exhaust valves in a diesel engine? （）A
They regulate the combustion cycleB
They supply cooling waterC
They synchronize the ignition sparkD
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cam followersB
push rodsC
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open late and close lateC
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line up the engine fore restarting with light diesel oilB
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单选题The process of scavenging a two-stroke/cycle diesel engine serves to（）A
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单选题In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.A
the beveled edges of the intake valves provide for serf-centering during seatingB
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单选题An indication of a diesel engine air intake being partially clogged, is （）.A
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单选题In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to（）.A
produce a scavenging effect in the combustion spaceB
equalize cylinder and exhaust manifold pressuresC
alleviate the difference in valve size between the intake and exhaustD
flush out condensate that collects after each compression stroke
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