为什么说a fun day 不说a funny day

为什么说a fun day 不说a funny day I didn't have a very fun day.中的fun是形容词还是名词,为什么 half a day 为何不说a half day what great fun it is to go camping in such fine weather,为什么不说what a great fun it is to gocamping in such a fine weather? half a day 为何不说half day.类比half apple today was a fun day.困扰 It's a fun day改为感叹句 Today was a fun day.同义句 make it a really fun day this->fun();为什么不可以写*this.fun() // A* a; a->fun(); *a.fun(); what fun it is to jump into a river on a hot day.为什么用what fun instead of how fun 为什么不能说a day,而要说one day 为什么说a room big enough而不说a big enough room what great fun it is to go hiking!为什么因为fun是不可数名词不加a,而不说它抽象名词具体化呢?还是因为fun不属于抽象名词具体化的范畴? It's ___to swim in the river with my friends in the hot day .A.a fun B.fun C.a funny选什么,为什么? watch tv为什么不说watch a tv? __ it is to have a cold drink on such a hot day!A.what a funB.how fun C.what funD.how a fun为什么?不能选B?fun是名词且不可数吗？ it is to go for a picnic on such a day!前面填什么A.what a fun B.what fun C.how funny D.how a fun为什么?