单项选择题
（）is the main reason that reduces the power advantage of a two-stroke engine over a same size four-stroke one to about（）
A.Inefficient scavenging；twice B.Inefficient scavenging；1~8 times C.Fewer strokes in a circle；twice D.Fewer strokes in a circle；1~8 times
单项选择题 In a diesel engine, when the fuel is injected into the cylinder,（）
单项选择题 One of the differences between a two-stroke engine and a four-stroke engine is,（）
