This is easy to understand, so that we can get closer to each other and look familiar and close. Just like when you consult customer service online, customer service usually says' pro', which is just a kind of address different from strangers and makes their relationship seem harmonious. Now when strangers say something to ask for directions in the street, they all call each other' beautiful and handsome', not that you are really beautiful and handsome, but a kind of address that distinguishes the sexes and makes strangers less embarrassed. Of course, if you are serious, you can at least have feelings for each other.