Chinlingo Chinese character: 旦

Ancient Chinese people created the character "旦" (dàn) based on their observation of astronomical phenomena. The character is up-down structured. "日" on the top means the sun, while "一" in the bottom refers to the horizon line. So "旦" meant "dawn or daybreak" originally. The sun rises from the horizon line and a new day starts.

中国古人观天象而造出了汉字"旦"（dàn）。此字为上下结构，上部为"日"指太阳。下部是长横，指代"地平线"。因此，"旦（dàn）"本义为"天亮、早晨"。即太阳从地平线上升起，新的一天开始了。

In modern Chinese, "旦" means "morning", and its antonym is "夕" (xī), which means "evening". So "旦夕" means "quite a short time" as a word. For example, the idiom "危在旦夕" (wēi zài dàn xī)  means "be in deadly danger". ("危", an abbreviation of "危险", means "danger"). We can say "人的生命危在旦夕" (someone's life is at death's door), or "某种局势紧迫，某个城市危在旦夕" (The city is in deadly danger as a result of an urgent situation). For example, "洪水淹没了村镇，城区危在旦夕", which means that "the flood has inundated villages and towns, and the urban area is in deadly danger". 

在现代汉语中， "旦（dàn）"指"早晨"，其反义词"夕"（xī）指"晚上"。 "旦夕"（dàn xī）可组成词语用来比喻很短的时间。比如，成语"危在旦夕"（wēi zài dàn xī），就是指危险将立即来临。（危：危险。）我们可以说，人的生命危在旦夕。也可以说，某种局势紧迫，某个城市危在旦夕。比如：洪水淹没了村镇，城区危在旦夕。

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