border ring

例句：

1. 1. The border ring is a symbol of national pride and cultural identity.
   边界环是民族自豪和文化身份的象征。
2. 2.The border ring was constructed to prevent illegal immigration.
   边界环的建造是为了阻止非法移民。
3. 3.The border ring is an important part of the national defense system.
   边界环是国家防御系统的重要组成部分。