单项选择题
A.fuel must be preheated
B.intake air should be preheated
C.lube oil outlet temperature should be increased 20℃ above normal
D.none of the above
单项选择题 Excessive diesel engine back pressure may be an indication of （）
单项选择题 A possible cause for an individual piston to knock when at TDC on a slow-speed, two-stroke/cycle main propulsion diesel engine could be due to （）
单项选择题 In a diesel engine, the time taken to heat the fuel particles, turn them into vapor, and bring about combustion is called （）