You see, the applicants in the office building are all neatly dressed and smiling, as if they are very close to the examiner. When they leave the examination room, they immediately straighten their faces and put back their smiles. Their ability to shrink and shrink is amazing; the colleagues around them are happily talking about things they think are funny. You don't want to expose the joke, so you smile as if it's the funniest joke you've ever heard in your life; the person you had a crush on got married, and you went to the banquet with an invitation, and when they met, you smiled as if you had never had a pure and careful relationship with the person in front of you...
Smiling all over the face may be a manifestation of an attitude when people ask for help, a way to avoid embarrassment, or a way to comfort themselves and conceal their feelings when they are helpless...