Which term describes piston pins having bearing surfaces in both the piston bosses and connecting rod eye?（）

单项选择题The longer the ignition delay period occurs in a diesel engine, the （）.

A.less fuel will enter the cylinder
B.lower will be cylinder compression temperatures
C.more complete will be fuel combustion
D.more rapid will be the rise in combustion pressure

单项选择题Poor combustion in a diesel engine can be caused by （）.

A.high compression pressure
B.low intake air temperature
C.low exhaust pressure
D.high scavenge air pressure

单项选择题High firing pressures and a low exhaust temperature in a diesel engine may result from （）.

A.decreased piston to cylinder head clearance
B.increased exhaust system back pressure
C.early fuel injection timing
D.low scavenge air temperature

单项选择题Whether using a centrifuge or a simple filter, oil cleaning and filtration will be the most effective when the oil is at a （）.

A.high temperature and a high viscosity
B.high temperature and a low viscosity
C.low temperature and a high viscosity
D.low temperature and a low viscosity

单项选择题Exhaust valve grooving and corrosion is caused by certain components of residual fuel oilThese components are sodium, sulfur, and （）.

A.vanadium
B.carbon
C.copper
D.ash