( ) great fun it must be to go abroad!这里的fun是名词还是形容词?

问题描述:

( ) great fun it must be to go abroad!这里的fun是名词还是形容词?
it must be fun,这个fun好象是形容词,

是名词,不可数名词,不是形容词
名词可以做表语和定语的,那个空应该填What(感叹句)
It is great fun to play here.