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' 。
Don't mind him.
别理他!
When a thief was caught on the premises of large jewellery store on morning, the shop assistants must have found it impossible to resist the temptation to say 'it serves him right.