topographic map symbols

例句：

1. 1.The topographic map symbols are used to indicate the elevation and terrain of the area.
   地形图符号用于指示该地区的海拔和地形。
2. 2.The topographic map symbols were designed to help people navigate the unfamiliar terrain.
   地形图符号的设计是为了帮助人们导航不熟悉的地形。
3. 3. The topographic map symbols are essential for understanding the geography of a region.
   地形图符号对于理解一个地区的地理至关重要。