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' 。
Only when he saw that the man was actually telephoning the police did he realize that they had all been the victims of a hoax.
当他看到那个工人真的是给警察挂电话,才恍然大悟,原来他们都成一场骗局的受害者。