四、請將下列英文譯成中文。(20 分) Water was the original hydraulic fluid, however, it is not a good lubricant since it promotes rusting and other forms of corrosion. Hydraulic oils may be straight mineral or special additive oils. Properties of these, enhanced by additives, include oxidation, stability, film strength, rust prevention, foam resistance and anti-wear characteristics to enable the fluid to stand up to the higher operating temperatures and pressures of modern systems.