regret一般意思是“遗憾，后悔”，但它的用法也是相当丰富的。
1. No regrets — 毫不后悔
例句：I lived life with no regrets. (我毫不后悔地过了自己的人生。)
2. Regrets only — 只接受请柬回复
例句：I’m having a party at my place next week, regrets only. (下周我在家开聚会，只接受请柬回复。)
3. Regrettable — 令人遗憾的
例句：It’s regrettable that she couldn’t join us. (她不能加入我们令人遗憾。)
4. Regretful — 遗憾的，后悔的
例句：I felt regretful for having said that to her. (我后悔对她说了那样的话。)
5. Regretfully — 遗憾地，惋惜地
例句：Regretfully, we have to decline the invitation. (很遗憾，我们必须拒绝邀请。)
6. Regrettable mistake — 令人遗憾的错误
例句：The accident was a regrettable mistake. (这次事故是一次令人遗憾的错误。)
7. Express/regret one’s apologies/respect/regards — 表示道歉/敬意/问候
例句：On this solemn occasion, I express my deep regret for what happened. (在这个庄严的场合，我为所发生的事情表示深刻的歉意。)
8. Live to regret — 后悔不已
例句：If you quit now, you’ll live to regret it. (如果你现在放弃，你将会后悔不已。)
9. Regret the day/night/moment — 后悔那一天/晚上/时刻
例句：You’ll regret the day you decided not to help me. (你将后悔当初决定不帮助我。)
10. Leave nothing to regret — 不留遗憾，无悔
例句：I want to leave nothing to regret. (我想要无悔的生活。)