After all, the Elphbergs are the royal family of Ruritania, and have been for hundreds of years.

老师，这句省略了表语吗、它省略了什么成分，为什么这样省略？

【翻译】毕竟，艾尔弗伯格家族是卢里塔尼亚的王族，而且，几百年来一直如此。

这个省略不是很明显吗？为了避免重复，为了简练，在have been后，承前省略了表语：the royal family of Ruritania。补充完整为：

and have been the royal family of Ruritania for hundreds of years.