russetting

例句：

1. 1.The old iron gate is starting to rust.
   那把旧铁门开始生锈了。
2. 2.The paint on the car has started to rust.
   汽车上的油漆开始生锈了。
3. 3.The metal surface is beginning to rust away.
   金属表面开始生锈并逐渐剥落。