vacuum refining

例句：

1. 1. The companyuses vacuum refining to remove impurities from its oil.
   该公司使用真空精炼来去除其油中的杂质。
2. 2. Vacuum refining is a crucial stepin the production of refined oil.
   真空精炼是生产精制油的关键步骤。
3. 3. During vacuumrefining, the oil is heatedand then cooled down to separate thedifferent types of fats.
   在真空精炼过程中，油被加热然后冷却，以分离不同类型的脂肪。