单项选择题
A.will lift B.will be lifted C.will close D.will be closed
The needle valve in a fuel valve will （） when the fuel ...
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
The most common cause of lowering the crankcase lube oi...
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
The mechanical efficiency of an engine （） because losse...
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%
