It's not something you're going to go back and remember it's an opposite side, it's an adjacent side.

不应该再去翻以前的课本,还去回忆哪个是对边,哪个是邻边

耶鲁公开课 - 基础物理课程节选

Typically, a mountain range will be the boundary between the area of two poleis or a stretch of water, because Greece has the sea winding through it everywhere.

比如,一座山脉,就能成为一种典型的城邦之间边界,由于希腊四处邻海,一段水域也可以成为边界

耶鲁公开课 - 古希腊历史简介课程节选