open pit boundary

例句：

1. 1.The open pit mine is located in the southern part of the country.
   露天矿位于该国南部。
2. 2. The boundary between the two countries is marked by a river.
   两国之间的边界由一条河流划分。
3. 3. The open pit mining method has been widely used in the extraction of metal ores.
   露天矿开采方法在金属矿石的提取中被广泛使用。