单项选择题
A.increases the density of the air
B.decrease the density of the air
C.increases the specific heat of the air
D.decreases the specific heat of the exhaust
单项选择题 Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because（）.
单项选择题 If the low level alarm of the diesel fuel day tank fails to function, you can expect trouble from（）
单项选择题 Before starting a diesel engine, you should always（）