These are all words for a line that marks the edge of sth and separates it from other areas or things. 以上各词均指边界、分界线。

• border the line that separates two countries or areas; the land near this line 指国界、边界、边疆、边界地区：◆a national park on the border between Kenya and Tanzania 位于肯尼亚和坦桑尼亚边界的国家公园
• boundary a line that marks the edges of an area of land and separates it from other areas 指边界、界限、分界线：◆The fence marked the boundary between my property and hers. 那道篱笆曾是我和她的房产之间的地界。
• frontier (BrE) the line that separates two countries or areas; the land near this line 指国界、边界、边疆、边境：◆The river formed the frontier between the land of the Saxons and that of the Danes. 这条河曾是撒克逊人与古斯堪的纳维亚人土地的分界线。

which word? 词语辨析

The point where you cross from one country to another is usually called the border. In British English it can also be called the frontier, but this is often in a context of wildness, danger and uncertainty. 国界线通常叫 border；英式英语亦可叫 frontier，但 frontier 常与荒芜、危险和不确定联系在一起：◆The rebels control the frontier and the surrounding area. 叛乱分子控制了边疆地区。The line on a map that shows the border of a country can be called the boundary but 'boundary' is not used when you cross from one country to another. 地图上标示的国界线可叫 boundary，但穿越国界不用 boundary：◆After the war the national boundaries were redrawn. 战后重新划定了国界。◆Thousands of immigrants cross the boundary every day. Boundary can also be a physical line between two places, for example between property belonging to two different people, marked by a fence or wall. * boundary 亦可指两地间的分界线，如用篱笆或墙隔开的分属于不同的两个人的土地分界线：◆the boundary fence/wall between the properties 分隔两所房子的篱笆/墙

Patterns

• across/along/on/over a/the border/boundary/frontier
• at the boundary/frontier
• the border/boundary/frontier with a place
• the northern/southern/eastern/western border/boundary/frontier
• a national/common/disputed border/boundary/frontier