（）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.

A . ignition lag B . engine horsepower C . lube oil system pressure D . specific fuel consumptio

A . has little or no internal friction B . has a lower effective compression ratio C . operates with scavenge air under a positive pressure D . operates without energy absorbing intake and exhaust stroke

A . open the bypass line B . cut in the lube oil cooler C . pressurize the lube oil system D . top off the expansion tank

A . cylinder liners and piston rings B . main bearings C . crankpin bearings D . turboblower

A . runs out of fuel B . has low lubricating oil pressure C . exceeds a set maximum speed D . has high cooling water temperature

A . natural aspiration B . masked intake valves C . air cells D . scavenging air

A . they are more heavily built B . the fuel used is less volatile C . they can be easily reversed D . they operate at a lower speed

A . valve guides B . oil control rings C . valve seats D . compression ring

A . crankcase pressure B . lube oil pressure C . saltwater pressure D . exhaust temperature

A . free entry of air to the crankcase B . water entering the crankcase while engine wash-downs are being performed C . excessive oil leakage during periods of increased blow-by D . sub-cooling internal component

A . blows out the exhaust gases B . supplies oxygen for combustion C . cools the valves and cylinder walls D . all of the above

A . 8-10℃ B . 10-12℃ C . 10-15℃ D . 10-20℃

A . delivering more air into the cylinder than it would normally receive during an ordinary charging process B . forcing the products of combustion out of the cylinder with the fresh air charge C . collecting the air charge at the cleaner D . combustion and expansion of hot ga

A . placed as near the crankpin axis as possible B . removed each time the crankshaft is repositioned C . left in place for all four readings D . reset to zero for all four reading

A . higher speed required B . flywheel-effect C . lower starting temperatures D . higher compression pressure

A . reducing exhaust gas velocity B . increasing the frequency of gas vibration C . the use of long head pipes D . the use of zinc electrode

A、A. turbine engine B、B. gas turbine C、C. steam engine D、D. internal combustion engine

A . opposed to the crankshaft rocking couple B . resonant with the crankshaft natural frequency C . critical fore and aft crankshaft vibrations D . horizontal whipping motions of the crankshaft

A . four cycle B . compression ignition C . vacuum ignition D . external combustio

A . cylinders B . exhaust valves C . pistons D . fuel valve

A . spark plugs B . glow plugs C . heat of compression D . a magneto

A . slam charger B . turbocharger C . fuel atomizer D . fuel injector

A . injecting fuel oil into a cylinder B . removing exhaust gases from the cylinder C . forcing air into the cylinders under pressure after the exhaust valve has dosed D . a combination of all the above

A . passing the exhaust through long head pipes B . diffusing exhaust vibrations through activated carbon baffles C . increasing the exhaust gas velocity D . reducing the exhaust gas velocity