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' 。
Big Ben takes its name from Sir Benjamin Hall who was responsible for the making of the clock when the new Houses of Parliament were being built.
“大本”钟得名于本杰明。霍尔爵士,因为当建造新的国会大厦时,他负责建造大钟。