You can't imagine_____ great fun chatting online is A what B how 选哪个?为什么?

问题描述:

You can't imagine_____ great fun chatting online is A what B how 选哪个?为什么?

A,因为fun是不可数名词,应与what相搭配

what
对名词fun感叹

You can't imagine_____ great fun chatting online is.
选A what
great fun是名词短语,所以用what