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

單項選擇題

Diesel engine mufflers or silencers reduce the engine exhaust noise by ()

A.passing the exhaust through long head pipes
B.diffusing exhaust vibrations through activated carbon baffles
C.increasing the exhaust gas velocity
D.reducing the exhaust gas velocity

微信掃碼免費搜題