What word does the old man use to sum up the photo exhibition?

The scenery is no longer (or "the good times don't last long")-the reason is that photography represents the scenery, and both people photography and scenery photography represent the beautiful scenery of the past. When the elderly look at these "scenes", they will bring back many good memories, and the memories of good memories will cause their own regrets such as "the good times are not long". This word can best describe this feeling of regret.