Which of the following devices is a common basic element with nearly all mechanical governors?（）

单项选择题A change in the degree of fuel atomization in a diesel engine would most greatly affect （）.

A.air turbulence
B.fuel penetration
C.fuel spray angle
D.fuel injection rate

单项选择题Scale and dirt accumulation in the waterside of a lube oil cooler will be indicated by a gradual increase in the lube oil（）.

A.TBN number
B.viscosity
C.temperature
D.foaming

单项选择题The lower section of a piston is called the （）.

A.land
B.skirt
C.crown
D.plate

单项选择题The diesel engine valve subjected to most severe conditions of service is the （）.

A.cylinder exhaust valve
B.air starting valve
C.air inlet valve
D.cylinder relief valve

单项选择题A piston in a four-stroke cycle diesel engine makes four strokes during each （）.

A.crankshaft revolution
B.mechanical cycle of operation
C.period of two combustion cycles
D.cycle of two events