单项选择题
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
单项选择题 If a diesel engine were running at 20% overload with a smoky exhaust, you should（）
单项选择题 A substantial increase pressure could be an indication of a/an （）
单项选择题 A water jacket is placed around the exhaust manifolds of propulsion diesel engines to（）
