middle line of wave height

例句：

1. 1.The middle line of the river is lined with trees.
   河的中线被树木环绕。
2. 2.The engineer drew a middle line to divide the land into sections.
   工程师画了一条中线，将土地分成几部分。
3. 3.The middle line of the road was clear, allowing easy passage for vehicles.
   道路的中线清晰，为车辆提供了畅通无阻的通行条件。