生水垢

例句：

1. 1. The water in the sink is turning into a layer of grime, which is not good for health.
   水槽里的水变成一层污垢，对健康不好。
2. 2. The old man's house has been covered with moss, making it look like a forest inside out.
   老人的房子被苔藓覆盖，看起来像森林里一样。
3. 3. The car engine is so dirty that it needs to be cleaned before it can run again.
   汽车发动机太脏了，需要清理才能再次运行。