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' 。
who produced it with a flourish and pointed out a microscopic 'o' beside the time of the arrival of the train at his station;
站长拿着时刻表一挥手,指着那趟列车到站时刻旁边一个很小的圆圈标记。