单项选择题
The needle valve in the injector （） at a pre-set pressure which ensures that the fuel will atomize once it enters the cylinder.
A.will lift
B.will be lifted
C.will close
D.will be closed
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相关考题
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单项选择题
The needle valve in a fuel valve will （） when the fuel pressure action on the needle valve tapered face exerts a force lower than that of the spring compression.
A.be jammed
B.be opened
C.be seated
D.be broken -
单项选择题
The most common cause of lowering the crankcase lube oil flash point is （）.
A.more water contents
B.contamination with fuel oil
C.higher temperature
D.sufficient cooling of oil mist -
单项选择题
The mechanical efficiency of an engine （） because losses occur in the form of friction.
A.is always less than 100%
B.is always more than 100%
C.is always equal to 90%
D.is always less than 90%
