四、請說明影響柴油機排氣溫度升高之原因及處理方法。（20 分）

五、將下列英文翻譯成中文：（20 分） The diesel engine piston is made of high grade cast iron suitable for high temperature and high pressure. The piston head is so shaped as to secure a good combustion. There are four piston rings at the upper part of the piston. The piston pin is inserted at its center and one oil ring each is equipped on its upper and lower side.