know something of everything but not everything of something
The five skills of the Chinese parasol are many but not excellent, which are useless in the matter. It comes from Xunzi's persuasion.
Idiom: Wuji
Pinyin: an analysis of idioms w ú sh ǔ w ǔ J ì
The Chinese parasol is poor in skills
Usage: as an object; refers to limited ability
Source: Xunzi's persuasion: "the snake flies without feet, and the rat is poor with five skills."
know something of everything but not everything of something
seeing the name of a thing one thinks of its function - gù míng sī yì
be busy enough with one 's own affairs - zì gù bù xiá