mean water river bed

例句：

1. 1.The mean water flows slowly through thevalley.
   这条河流缓慢地流过山谷。
2. 2.The riverbed is covered in rocks andpebbles.
   河床覆盖着岩石和卵石。
3. 3. The riverbed is apopular spot for fishing and hiking.
   河床是钓鱼和徒步旅行的热门地点。