早知今日何必當初

1. • if I (you, she, he...) had known it would come to this, I (you, she, he...) would not have acted thus (idiom)
2. • to regret vainly one's past behavior

Character by character

• 早(zǎo)early
• 知(zhī)know
• 今(jīn)now
• 日(rì)sun
• 何(hé)surname He
• 必(bì)certainly
• 當(dāng)be
• 初(chū)at first