“痛改前非”，汉语成语，意思是彻底改正以前所犯的错误。可以翻译为“sincerely mend one's ways或thoroughly rectify one's errors”等。

例句：

痛改前非，重新做人

sincerely mend one's ways and turn over a new leaf

他来信表明愿意痛改前非。

His letter bespeaks his willingness to mend his ways.