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

In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because ().

A.the beveled edges of the intake valves provide for serf-centering during seating
B.intake valves utilize stellite-coated valve seat inserts which reduce wear
C.the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
D.intake valves are less affected to the corrosive action of exhaust gases

微信掃碼免費(fèi)搜題