单项选择题
A.reduce engine exhaust noise
B.reduce engine back pressure
C.recover heat which otherwise would be lost
D.increase turbocharger efficiency
单项选择题 The principal difference between loop scavenging and crossflow scavenging, as used in single acting diesel engines, is the （）
单项选择题 Oxygen corrosion in auxiliary boilers is prevented by treating the boiler feed tank with either sodium （）
单项选择题 Operating a diesel engine for prolonged periods, with a closed freshwater cooling system, at temperatures lower than the normal design temperature can cause （）.