那抹天真却留给了曾經那抹天真却留给了過去
[nèi mŏ tiān zhēn què liú jĭ le céng jīng nèi mŏ tiān zhēn què liú jĭ le guò qù]
This expresses nostalgia for past naivety and innocence which belonged to former times ('过去'). It reflects someone reminiscing about youthful, more innocent days compared to current maturity.