过不去的过去怎叫过去放不下的曾经怎叫曾经
[guò bù qù de guò qù zĕn jiào guò qù fàng bù xià de céng jīng zĕn jiào céng jīng]
The past that cannot be moved on from isn't really past; memories too hard to let go can hardly be called mere past. This suggests difficulty with accepting change or letting go of old times or feelings.