Last name+official title. The person who calls himself the manager in the unit group is surname+official title. Such as Manager Li and Manager Zhang. When addressing colleagues, you should address your older brothers and sisters, younger brothers and sisters, or directly address them as the youngest+surname, such as Lao Li, Xiao Zhang, Liu Jie, Wang Laodi, etc. Or by first name. In short, treat the leaders and colleagues of the working group of the unit with respect, kindness, modesty and warmth.