axis of stream bed

例句：

1. 1. The stream bed is covered in lush green grass.
   这条河床覆盖着茂密的绿色草地。
2. 2. The engineer studied the stream bed to determine its stability.
   工程师研究了河床以确定其稳定性。
3. 3.The construction crew carefully excavated the stream bed to build the new bridge.
   施工队小心翼翼地挖掘河床，建造新的桥梁。