为什么不能说it is a great fun?不是说抽象名词前有修饰就可以用冠词了么?great不能算修饰么?

为什么不能说it is a great fun?不是说抽象名词前有修饰就可以用冠词了么?great不能算修饰么? what nice food it is!的句子成分 为什么不能说是what a nice food it is!为什么不能说how a nice food it is! what's this?It's a pen.为什么不能说是this is a pen.我们老师说就是不能说this is a pen.为什么 the indoor seimming pool seems to be a great deal more luxurious than__为什么一定要选is necessary不能选it is necessary呢? 为什么what great fun it is 这个句子里,great前没有a? today is a great day.可以这样说吗?还是it is a great day today.并延伸. What a great movie it is It is a great postcard.变感叹句 It is a great piace to learn 修改病句It is a great successful. great a difficulty as it is可以这样说吗 有关as 的句型 great fun ,但不是说 抽象名词有修饰词,可以加不定冠词吗?如 a great success为什么不能写成a great fun it is a great fun 还是it is great fun居然年级第一说 前者 那么到底是前者还是后者? 帮忙修改一句话（英语的）What a delicious food it is!哪错了？为什么不能这样说？ what great fun it is to go hiking in such fine weather!和what a great fun .!哪个对?为什么? what make is it 为什么不能说成it is what make 或者是it is make 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? 【英语】“I consider it a great honor.”中为什么不是“...it is a great .”呢?还有“ consider it necessary to do sth.”