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' 。
When you rescued your trousers, did note in your back pocket? When you rescued your trousers, did you find the note was whiter than white?
当你把裤子抢救出来时,你有没有发现那张纸币已经变得比白纸还白?