"he drank to drown his sorrows"
"he wrote a note expressing his regret"
"to his rue, the error cost him the game"
"I regret I can't come to the party"
"I regret to say that you did not gain admission to Harvard"
I regret to tell you that my brother died yesterday afternoon.
我很遗憾地告诉你,我哥哥昨天下午去世了。
I regret to hear of your sister's death.
我为你妹妹的死而感到悲哀。
I regret causing him so much inconvenience.
我因让他如此不方便而感到后悔。