Using (y ǒ u j and k ch é ng) means having the opportunity to use it, and there are loopholes to drill. From Ming Luo's "Romance of the Three Kingdoms" Guan Zhong for the hundredth time: "Wei has a gap to take advantage of today, why not cut it at this time?"

One thousand Ali days (y and rqiā n lǐ) shows that horses run very fast and can run one thousand Ali days. The latter metaphor has made rapid progress.

Source: Zhuangzi Qiushui: "Qi, Ji, Hua, Qi, a thousand miles a day." "Historical Records Biography of Assassins": "I heard that Miracle is prosperous, thousands of miles away; To its aging; Drive the horse away first. "