Basic interpretation: the same as "laugh". Zhao Hou said, "I heard that your master loves to laugh, and those who laugh can do something. How nice these pants are! Those who make meritorious deeds, I will stay. " Han Zhaohou said, "I know that a wise monarch cherishes every movement, a frown and a smile, all of which can be felt. Now these pants are more important than frowning and smiling. You must wait until someone makes meritorious deeds. " )-History as a Mirror Volume II refers to smiling with your mouth closed, which can be understood as "smiling without showing your teeth" or "smiling without saying anything".