乌有

tā de cái fù yǐ huà wéi wū yǒu

她的财富已化为乌有。

Her fortune has dwindled to nothing.

zhè ge gài niàn bù guò shì zǐ xū wū yǒu

这个概念不过是子虚乌有。

The notion is nothing more than a myth.