rue
/ru:; ru/ n [U]
type of evergreen shrub with bitter leaves formerly used in medicine 芸香（常绿灌木, 叶味苦, 旧时用以入药）.
rue / ru:; ru/ v (pres p rueing or ruing, pt, pp rued) [Tn]
(dated or fml 旧或文) repent or regret (sth) (used esp in the expressions shown) 对（某事物）感到懊悔（尤用於以下示例）
You'll live to rue it, ie You will regret it one day. 总有一天你得後悔.
He's rueing the day he joined the Army! 他後悔参了军!