回天乏術

To return; to go back; to reply or answer; to turn around; a time or occurrence; classifier for acts of a play or chapters; the Hui ethnic group.

Sky or heaven; the universe; day or a period of time; nature; weather; season.

To lack; to be short of; to be tired or exhausted; poor or impoverished.

Method or technique; skill or art; a special feat or trick; a strategy or plan; archaic administrative region outside a city.