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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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单选题In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressureA
ⅠonlyB
ⅡonlyC
bothⅠand ⅡD
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high compression pressureB
low intake air temperatureC
low exhaust pressureD
high scavenge air temperature
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单选题A diesel engine emits blue exhaust smoke as a result of（）A
cold intake airB
excessive compression pressureC
excessive cylinder lubricationD
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the proper back pressureB
the cooling water temperatureC
correct timing and proper seatingD
accurate metering and the exhaust temperature
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单选题A dark exhaust from a running diesel engine can be caused by （）A
late ignitionB
water in the fuelC
high compression temperatureD
starting valve stuck open
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单选题What is the purpose of the intake/exhaust valves in a diesel engine? （）A
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They synchronize the ignition sparkD
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单选题The intake valves in a diesel engine are reseated by （）.A
cam followersB
push rodsC
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单选题If the valve tappets in a diesel engine are set at greater clearances than those specified by the engine manufacturer, those valves will （）A
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last part of the exhaust stroke, and the first part of the intake strokeB
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单选题A two-stroke/cycle diesel engine requires less starting air than a four-stroke/cycle diesel engine, of equal displacement, because the two-stroke/cycle diesel engine（）A
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单选题Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）A
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单选题The process of scavenging a two-stroke/cycle diesel engine serves to（）A
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考题
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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考题
单选题An indication of a diesel engine air intake being partially clogged, is （）.A
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low firing pressure and normal exhaust temperaturesC
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单选题A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated four-stroke/cycle diesel engine, in order to in crease the （）.A
temperature of the exhaust gasesB
energy supplied to the turbochargerC
air pressure to the intake manifoldD
purge of exhausted gases from the cylinders
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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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