hinges
A hinge is a piece of metal, wood, or plastic that is used to join a door to its frame or to join two things together so that one of them can swing freely.
The top swung open on well-oiled hinges.
合页润滑得很好,盖子一下子就开了。
hinges , hinging , hinged
hinge on
Something that hinges on one thing or event depends entirely on it.
The plan hinges on a deal being struck with a new company.
该计划完全取决于正在和一家新公司洽谈着的一笔交易。