An annual book festival in west Los Angeles is "sold out" year after year.

问题描述:

An annual book festival in west Los Angeles is "sold out" year after year.
请翻译这个句子,并说明is "sold out"的意思和句子成分.

洛山矶西部的年度书节年年都很卖座!(卖空了!)
sold out应该充当表语成分,而不应该看做被动式!