corner stone

基本解释

Suddenlyhe had turned the corner by the stone shelter.
突然，他拐到石头后面一块隐蔽的地方。
Ever since the concept of sovereignty has been defined, for the past hundreds of years, this principle has been the corner stone of the modern international legal system.
自国家主权这个概念提出以来，经过几百年的发展，主权原则已经成为现代国际法体系中的最重要的原则之一。
The task of increasing employment is arduous now and will remain so for a long time to come. Moreover, It is the Corner Stone of Building a Well - off Society in an All - round Way.
扩大就业是我国当前和今后长时期重大而艰巨的任务，也是全面建设小康社会的基础。

Everywhere you looked, one of them seemed to be staring at nothing, drinking it in, transfixed: a dead stalk of dock weed or the blank corner of a stone wall or an icicle dribbled from the lip of a gutter.
NEWYORKER: She’s the One
DC, notice the massive stone boxes in a corner of the cemetery which hold thousands of unknown soldiers killed in the Civil War of 1861-65.
ECONOMIST: Known unto God, and DNA
When the train stopped at a station in that country, the police dragged Narayana off the train and put him in a small eight-foot-by-eight-foot room with a cold stone floor and a hole in the corner that served as a toilet.
FORBES: Entrepreneurs Who Changed Business as We Knew It

The cornerstone of something is the basic part of it on which its existence, success, or truth depends.