flume with side contraction

例句：

1. 1. The river flows through the valley, creating a beautiful flume.
   这条河流经山谷，形成了一道美丽的峡谷。
2. 2. The engineer designed a new flume to improve water flow efficiency.
   工程师设计了一个新的渠道来提高水流效率。
3. 3. The construction of the flume has been completed, and it is now open for tourists to enjoy.
   渠道的建造已经完成，现在对游客开放。