记忆像散落的纸碎片拾不起
[jì yì xiàng sàn luò de zhĭ suì piàn shí bù qĭ]
'Memories are like scattered paper pieces unable to pick up'. Here implies many old recollections are fragmented into tiny pieces due to long time passed or certain accidents and are hard to reassemble completely now. It conveys a feeling of nostalgia for something impossible to retrieve as a whole as it used to be before.