切肤之痛------No one knows where the shoe pinches like the wearer

例句：
A:After her father died, she felt rather sad.
她的父亲去世后，她感到相当伤心。
B:It's really a sad thing which no one knows where the shoe pinches like the wearer.
那的确是件令人伤心且为切肤之痛的事。