英语句式分析,后半句做句子什么成分?

问题描述:

英语句式分析,后半句做句子什么成分?
I would be grateful if you could find a single room for me , preferably not in the same building but as near to the college campus as possinle. 逗号的后半句在整个句子中是什么成分?是省略了which is 吗?

作a single room中room的后置定语,可以看做两个介词短语那这个preferably怎么理解呢?