单项选择题
Defective air cooler in a diesel engine will lead to （）.
A.smoky exhaust B.starting failure C.overload D.over speed
单项选择题 Defective atomizer in a diesel engine will lead to（）.
单项选择题 A supercharged engine differs from an un-supercharged engine it operates at an increases pressure（）.
单项选择题 Cooling makes the engine metals their mechanical properties（）.
