What great fun和What a great fun哪个才是正确的?

What great fun和What a great fun哪个才是正确的? what great fun\what a great fun.哪个对 请问那个正确 What a great fun it is to go surfing; What great fun what a great fun/what great fun为什么不可以用how great fun what a great fun swimming in the river...和what great fun swi what a great fun it is to go fishing和what great fun it is to what a fun和what fun哪个对 我记得好像有个what a great fun 所以我认为你what a 英语的fun可数吗?是What a great fun it is!还是What great fun it is! great fun 和a great fun fun 可数吗,What.a great fun it is .正确吗 What a great fun it is to go surfing; What great fun it is t 为什么是what great fun it is!而不是what a great fun it is!