一脸无辜不代表你懵懂
[yī liăn wú gū bù dài biăo nĭ mĕng dŏng]
'Looking Innocent Doesn't Mean You're Naive'. This expresses awareness that although appearance may give an innocent impression, it does not equate ignorance. Instead, it signifies a mature attitude towards facing things with clear-headedness regardless of how innocent one looks externally.