单项选择题
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 strokes
单项选择题 Which of the following operating conditions can occur when shims are removed from the joint between the foot of a marine type diesel engine connecting rod and the bearing box?（）
单项选择题 The longer the ignition delay period resulting from improper use of low cetane fuel, the （）
单项选择题 Intercoolers installed on starting air compressors, reduce the possibility of（）