前沿地

例句：

1. 1.The frontier between the two countries is still a point of contention.
   两国之间的边界仍然是争议的焦点。
2. 2. The frontier researcher has made significant discoveries in this field.
   这位边疆研究者在这片领域取得了重大发现。
3. 3. The frontier of human knowledge is constantly expanding.
   人类知识的前沿不断扩展。