hardened way

例句：

1. 1. Themetal has been hardened by the heat.
   金属因高温而变硬了。
2. 2.The road was hardened by years of use.
   这条路因多年的使用而变得坚硬。
3. 3.The rock is hardened by pressure and time.
   岩石因压力和时间而变硬。