例句：
This would be regrettable.
這將令人遺憾。
Visitor a: Oh, it's so regrettable!
參觀者A：啊，太遺憾了！
He has committed a regrettable mistake.
他犯了一個令人遺憾的錯誤。
What's wrong with regretting?
后悔有什么不好？
It is no use regretting the past.
后悔過去是沒有用的。
He was regretting he'd called Mick now.
他現在在后悔給米克打了電話。