户枢不朽

Explanation: A door hinge: the door of the shaft; rot: rotten, corrupt. Axis of rotation of the door often will not decay. By analogy 　　Source: "Three Kingdoms Wu Chuan-Pu": "shake the Valley angry consumption, blood flow, patients may not students, give an example there is a door hinge is also immortal." Thesaurus:  a door-hinge is never worm-eaten, Glide Not rot, Running water is never stale and a door-hinges never get worm-eaten, practice keep one always fit, Door pivot Not Gryllotalpa africona