单选题Diesel engine mufflers or silencers reduce the engine exhaust noise by （）Apassing the exhaust through long head pipesBdiffusing exhaust vibrations through activated carbon bafflesCincreasing the exhaust gas velocityDreducing the exhaust gas velocity
单选题
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
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