trochal

例句：

1. 1.The old iron gate is covered in a thick layer of rust.
   那把旧铁门上覆盖着厚厚的一层锈。
2. 2. He noticed the rust on the metal surface.
   他注意到了金属表面的锈迹。
3. 3. The rusted nails were difficult to remove from the wall.
   生锈的钉子很难从墙上拔下来。