fringe region of the atmosphere

例句：

1. 1. The fringe of the forest is denser than the center.
   森林的边缘比中心更密集。
2. 2. The fringe of the crowd parted to let him pass.
   人群的边缘让开让他过去。
3. 3.The fringe of the ocean is often covered in sand.
   海洋的边缘通常覆盖着沙。