单项选择题
In using reduction gears to obtain efficient propeller speeds, （）.
A.they must be located at the after end of the engine B.they can only be used with one engine at a time C.they eliminate the need for controllable pitch propellers D.they are connected to the engine with a flexible coupling
单项选择题 Combustion knock occurring in a diesel engine can be caused by （）.
单项选择题 A thrust bearing is used with a propulsion diesel engine to （）.
单项选择题 Control of the main propulsion diesel engines can be shifted from the engine room to the wheelhouse from the （）.
