n.命脈；生機的根源

Trade is the lifeblood of our country. 貿(mào)易是我國的命脈。

Tourism is the area's lifeblood. 旅游業(yè)是這一地區(qū)的命脈。

Teachers are the lifeblood of a school. 老師是學(xué)校的靈魂！

The girl is the lifeblood of her mother. 這女孩子是她母親的命根子。