英语句法分析，各位帮我看看后面的是什么成分？

Question

The room was served as a small hall for important vistor.
主语：The room 谓语：was served 介宾：as a small hall .后面的：for important vistor .是宾语补足语还是定语？为什么？

Answer 1

for important vistor 是状语。因为它修饰的并不是small hall，而是谓语动词serve.

这间房被用作一个接待贵客的小会堂。

Answer 2

当然是定语a small hall for important vistor
显然for important vistor作后置定语

Answer 3

定语，用来修饰限制a small hall 。