单项选择题
Which condition indicates the air side fouling of an after-cooler on a turbocharged diesel engine?（）
A.An increased air temperature differential between the cooler inlet and outlet
B.A decrease in the air pressure differential across the cooler
C.Excessive condensate forming in the air box
D.A decrease in the air temperature differential between the cooler inlet and outlet
单项选择题 Black areas on the sealing surfaces of piston rings indicate（）
单项选择题 When inspecting piston rings through the ports of a two-stroke/cycle diesel engine, black areas on the sealing surfaces are the result of （）
单项选择题 Visual inspection of chrome-plated piston compression rings reveals a black ring face at the position of the cylinder liner portsThis condition indicates a ring which（）