欠情 To owe feeling. To have received a kindness and not yet repaid it. In The Plum in the Golden Vase, a man greets another: “I have owed you feeling for a long time and have not come to see you, brother.”
领情 To receive feeling. To accept a gift or a kindness and feel grateful for it.
回礼 To return a courtesy. To answer a gift or a greeting with one of one’s own.
雪中送炭 To send charcoal in the snow. To help someone in urgent need. A Ming story sets it against 锦上添花, adding flowers to brocade: “There is only adding flowers to brocade. Where is there sending charcoal in the snow?”