oil hardening

例句：

1. 1. The process of oil hardening is crucial for the stability of the oil.
   油硬化的过程对油的稳定性至关重要。
2. 2.During the oil hardening process, the temperature must be carefully controlled.
   在油硬化过程中，温度必须小心控制。
3. 3. The oil hardening agent was added to the oil before it was poured into the mold.
   在将油倒入模具之前，先加入了油硬化剂。