You have to mix oil into the gas in a two-stroke engine because the holes in the cylinder wall prevent the use of rings to seal the combustion chamber.
在二冲程发动机中你必须混和燃料和气体，因为气缸壁上的孔阻止使用活塞环密封燃烧室。
2
Otto built the practical four-stroke internal combustion engine called the "Otto Cycle Engine, " and as soon as he had completed his engine, he built it into a motorcycle.
The authors consider that increasing the piston stroke is an effective scheme, and point out that the petaloid combustion chamber has a good adaptability.