Joke Collection Website - Bulletin headlines - Two people exchange gifts, one gives the other a big gift, and the other gives him a small gift. What is this idiom? Guess idioms crazily

Two people exchange gifts, one gives the other a big gift, and the other gives him a small gift. What is this idiom? Guess idioms crazily

Idiom: Courtesy is reciprocated.

courtesy demands reciprocity

[Interpretation] Shang: Attention. It means that etiquette should give and take. Now it also means to answer each other with the same attitude or practice.

[Source] Song Hu Yin's "Non-Ji Ran": "Courtesy and reciprocity, think about it; Deeply attracted by repeated brick throwing. "