alternate scour

例句：

1. 1. The river has an alternate scour that can be dangerous for swimmers.
   这条河有交替冲刷，对游泳者来说可能是危险的。
2. 2.During the construction, the workers had to alternate scour the area with sand and water.
   在施工期间，工人们必须轮流用沙和水清理这个区域。
3. 3.The team decided to alternate scour different parts of the field to ensure uniformity in the crops.
   该团队决定轮流检查田地的不同部分，以确保作物的均匀生长。