Its cresting front segments threw a sandwave that would sweep across his knees.

它的顶峰前段抛出的沙浪会扫过他的膝盖。

It appeared to be more than half a league long, and the rise of the sandwave at its cresting head was like the approach of a mountain.

它似乎有半里格多长，在它的顶峰处掀起的沙浪就像一座山的逼近。