If you don't know a person's last name, use 'ma'am' or 'sir'.
如果你不知道一人的姓, 你应称呼他为 'ma'am' 或 'sir' 。
Indeed, it may well be that those whose work is their pleasure are those who most need the means of banishing it at intervals from their minds.
说实在的,把工作当作享受的那些人可能最需要每隔一段时间把工作从头脑中撇开。