五、請將下列英文譯成中文。（20 分）To ensure trouble-free operation of water-tube boilers the feed water must be of highquality with a minimal solid content and an absence of dissolved gases. Solids aredeposited on the inside surfaces of steam generating tubes, as the water boils off, and thescale so formed causes overheating and failure. Dissolved gases tend to promotecorrosion. Distilled water used as boiler feed has a great affinity for gases in theatmosphere. Chemical treatment is aimed at preventing corrosion problems but the boilerclosed feed system must play its part in maintaining minimal contact between feed waterand air at every stage and in promoting the dissociation and removal of any air or othergases.