life·blood /ˈlaɪfˈblʌd, ˌblʌd/
鮮血,血,生機的根源
Life·blood n.
1. The blood necessary to life; vital blood.
2. Fig.: That which gives strength and energy.
Money [is] the lifeblood of the nation. --Swift.
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lifeblood
n 1: the blood considered as the seat of vitality
2: an essential or life-giving force; "water is the lifeblood
of India"