1. There is no room for hair, Chinese idiom, pinyin is jiān bù róng fà, which means that there is no room for a hair in the gap. It describes the extremely small distance between things, and also describes the extremely close distance between disasters and extremely critical situations. . It comes from "A Letter to Admonish the King of Wu" written by Meicheng of the Han Dynasty.

2. The source of the idiom:

Han Dynasty Meicheng's "A Letter to Admonish the King of Wu": "It is tied to the sky and cannot be re-tied. It falls into the abyss and is difficult to come back. It cannot come out." There is no time to go out."