what a great fun it is to go fishing和what great fun it is to go fishing哪个是正确的?

问题描述:

what a great fun it is to go fishing和what great fun it is to go fishing哪个是正确的?
不是说抽象名词可以具体化吗?去钓鱼是多么开心的一件事啊!有什么不对吗

What great fun it is to go fishing!是正确的
前者的错误出现在fun是不可数的,不能称之为“a fun”