单项选择题
The （） engine is used for alternators and some times for main propulsion with a gearbox to provide a propeller of between 90 to 120 rpm.
A.four-stroke B.two-stroke C.slow speed D.reversible
单项选择题 The （） of the main shaft should be measured with a （）.
单项选择题 Such an engine frame helps （） the engine and so protect the bearings from the deformation forces transmitted via the ships double bottom.
单项选择题 “Stand by engine” means （）.
