97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区 狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

單項(xiàng)選擇題

Exhaust gases are generally removed from the cylinders of a two-stroke/cycle diesel engine by()

A.natural aspiration
B.masked intake valves
C.air cells
D.scavenging air

微信掃碼免費(fèi)搜題