申論 5請將下列專業英文翻譯成中文。（20 分）Controllable pitch propellers are normally fitted to a flanged tail shaft as theoperating mechanism is housed in the propeller boss. As its name implies, itis possible to alter the pitch of this type of propeller to change ship speed or toadjust to the prevailing resistance conditions. This change in pitch is effectedby rotating the blades about their vertical axes, either by hydraulic ormechanical means. A shaft generator can be driven at constant speed whileallowing at the same time a change of ship’s speed through the propeller. Sinceit is normally possible to reverse the pitch completely, this type of propeller isused with a unidirectional engine to give full ahead or astern thrust, whenmaneuvering.