四、試說明船舶柴油主機之轉俥機功能。（20 分）

四、請將下列輪機英文翻譯成中文：（25 分） Theoretically, the two-stroke cycle engine, with one working or power stroke every revolution, develops twice the power of a four-stroke engine of the same swept volume. The four-stroke engine rotating at medium speed, usually between 250 and 750 rev/min, is used for auxiliaries such as generators and sometimes for main propulsion with a gearbox.