stream hardening

例句：

1. 1.The stream flowed slowly through the forest.
   这条小河缓缓流过森林。
2. 2. The stream was crystal clear and inviting for swimming.
   这条小河清澈见底，非常适合游泳。
3. 3.The stream provided a source of water for the town.
   这条小河为小镇提供了水源。