根据柯林斯英语语法系列《限定词及数量词》：在肯定语境中，very much 通常仅用作副词。若用 very much 作限定词或代词，它则必须用于非肯定语境。

所以very much 可以用作主语或宾语（当它用作代词时），但通常只限于非肯定句中。

▲very much 可以用作宾语（动词宾语和介词宾语），注意主要限于非肯定句。如：

These clues don’t really add up to verymuch. 这些线索没什么实际意义。

He didn’t really know very much about javelin throwing. 他其实并不太懂掷标枪。

Statistics and surveys often don’t prove very much at all. 数据和调查常常证明不了什么。

His evidence didn’t really add up to very much. (= gave us very little information). 他的证词实际上说明不了什么问题。

▲very much 也可以用作主语，但也通常用于非肯定句中。在手头的词典上没有找到相关例句，但在BNC（英国国家语料库）上查到了几例（虽然不如纸质词典权威，就当作个参考吧）：

Yet not very much seems to have been done to make that wall unclimbable.

Banbury School opened its doors on 1 September 1967, but not very muchchanged on that day.

Not very much is known aboutLloyds so it's somewhat more mystical than an ordinary club.