kindly in appearance but unfathomable at heart
He is kind in appearance but unpredictable in heart. It's the same as "deep feeling".
Idioms and allusions
Source: Qing Dynasty, Chen Menglei's "friendship breaking book": "swear to heaven, thick appearance and profound writing, enough to move."
Discrimination of words
Usage: as predicate, attribute; refers to the appearance of kindness, the heart is unpredictable.
Chinese PinYin : hòu mào shēn wén
kindly in appearance but unfathomable at heart
big in stature and eminent in virtue without comparison. shuò dà wú péng
Speaking of Cao Cao, Cao Cao will arrive. shuō dào cáo cāo,cáo cāo jiù dào
Consider the past and the present. zhuó gǔ cān jīn
Golden rules and jade sentences. jīn zhāng yù jù