单项选择题
A.Diesel engine propulsion
B.Diesel electric propulsion
C.Steam engine propulsion
D.Gas turbine propulsion
单项选择题 （） can be found on most medium to large merchant vessels even if the main engine is either a steam turbine or 2-stroke crosshead engine.
单项选择题 The difference between a supercharged engine and an un-supercharged engine is that （）.
单项选择题 （）, the following possible causes should be investigated.