frontier
单词辨析：
多指靠近两国或两地区分界线的区域。
the German-Polish border
德国与波兰边境
Two years later, he was sent to the border between China and Myanmar.
两年以后，他被派到了中缅边界。
侧重指某区域最外的界线，常和领土有关，也指地图上正式标定的、双方认可的边界或较小行政单位间的界线。
national/state/city boundary
国界/州界/市界
They marked the boundaries of the basketball court.
他们标出了篮球场的边界。
The river forms the boundary between my land and his.
这条河构成了我这块地和他那块地之间的分界线。
指两国接壤的前沿地区，多有军队驻防。
China has a frontier with Vietnam.
中国的边界和越南相接。
Soldiers guard the frontier against invasion.
战士们守卫边疆，防止外敌入侵。
相关例句：
Abstract: some frontier technologies and design concepts in the development of analytical instrumentation in recent years are reviewed.
文摘：评述了近年来现代分析仪器发展的前沿技术和设计思想。
Your country and mine have a common frontier.
你的国家和我的国家有一条共同的边界。
The local people's government should support the construction of the institutions and facilities of the frontier ports.
地方人民政府要支持边境口岸机构和设施的建设。
The frontier guards together with the militiamen drove out the invaders.
边防战士和民兵一起把入侵者赶了出去。
The revolving movement of M-V portfolio efficient frontier is given by means of efficient security and inefficient security.
引入了有效证券和无效证券，给出了M-V证券组合有效前沿旋移的方向。
Then it indicates that the ecology of Salt-sea does harm to Central Asia and the north-west frontier in China.
其次说明了咸海生态危机对中亚和中国西北边疆造成的危害。