为了描述某个历史时期自然界和人类社会发展的过程,或者某种事物的发展过程和个人经历,往往要用起迄年份来表示时间跨度。如:孔子(公元前551～前479),表示孔子活了72岁;西汉(公元前206～25年),表示西汉延续时间231年;元武宗(1303～1311年在位),表示元武宗当了4年皇帝; In order to describe the process of the development of nature and human society in a historical period, or the development process and personal experience of a certain kind of thing, it is often necessary to express the time span from year to year. Such as: Confucius (551 BC ~ 479 BC), said Confucius lived for 72 years; Western Han Dynasty (206 ~ 25 BC), said the Western Han Dynasty continued for 231 years; Yuan Wuzong (1303 ~ 1311 reign), said Yuan Wuzong 4 years as emperor