单项选择题
A.a single, long-stroke, slow-speed, turbocharged, two-stroke diesel engine
B.a single, long-stroke, medium-speed, turbocharged, four-stroke diesel engine
C.two medium-speed, turbocharged, four-stroke diesel engines
D.a variable-speed AC generator
单项选择题 Propulsion of the vast majority of contemporary merchant ships (especially containerships and VLCCs) utilizes（） as prime mover.
单项选择题 （）are increasingly used as main engine on merchant vessels, because they have a high Hp/Weight ratio.
单项选择题 During check on top clearance in main bearings, turn the crankthrow for the relevant cylinder unit to （） and stop the lube oil circulating pump.