Correct

莫测高深

/ mò cè gāoshēn /
Strokes

Definition

enigmatic/beyond one's depth/unfathomable

Example

Definition

enigmatic; unfathomable; mystifying

1
Lǎorén
老人
gāoshēn
莫测高深
de
biǎoqíng
表情
  
,
ràng
men
我们
cāi
bu
tòu
zài
xiǎng
shénme
什么
  

The old man's enigmatic expression gave us no clue as to what was going on in his mind.