boundary line 有形的~线visible boundary line/无形的~线invisible boundary line/陆地~线boundary line on land 相关词汇 传统习惯线 traditional customary boundary line 实际控制线 line of actual control 起点 starting point;initial point 终点 terminal point;terminus 东端 eastern extremity 西端 western extremity 东段 eastern sector 西段 western sector 中段 middle sector