知根知底
zhī gēn zhī dǐ
to know someone inside out: their family, past and character
Character by character
知zhī
know
know
根gēn
root
root
知zhī
know
know
底dǐ
bottom
bottom
Example
我们是一个村长大的，彼此知根知底，你放心吧。
We grew up in the same village and know each other inside out, so don’t worry.
Tone: neutral.
Usage and origin
Said of people you can trust because you know where they come from: 知根知底的老朋友, 找个知根知底的人. It explains why so many jobs, from nannies to business partners, still go through relatives, neighbours and 老乡.
Learn this in Lesson 134 · HSK 7–9: 家政阿姨与月嫂 (Housekeepers and maternity nurses)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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