The idiom **危在旦夕 (wēi zài dàn xī)** is formed through a classical Chinese grammatical structure where **危** (wēi, meaning "danger" or "peril") is the subject of the state, and **在旦夕** (zài dàn xī, meaning "is in the morning and evening") acts as the predicate, creating a vivid metaphor. Literally, it states that the danger exists within the span of a single day—from **旦** (dàn, dawn) to **夕** (xī, dusk). This juxtaposition of imminent danger with the shortest natural cycle of time figuratively conveys a sense of extreme and immediate urgency, implying that a catastrophic outcome is moments away.