为什么 I am Chinese中没有冠词a

为什么 I am Chinese中没有冠词a I am Chinese.VS I am an American.有人说：只有I am Chinese.没有（或者说不正规）I am a Chinese.那为什么有I am an American.(我认为有)顺便问下在“I am Chinese”中,Chinese是名词还是形容词? I am Chinese boy.chinese为什么不能用china代替 I am Chinese.中Chinese前用不用加a? I am a Chinese girl.为什么不用:I am an Chinese girl. 要表达我是中国人应该说I am Chinese为什么不说I am a Chinese? I am not Chinese boy I am not a Chinese 为什么后者要加a那 i am not chinese i am nativer chinese i am proud i am a chinese I am Chinese.Chinese的词性 I am a Chinese还是I am Chinese 是i am a chinese 还是 i am chinese I am Chinese.I am a Chinese.哪个句子正确 为什么不能说I am an English?我们可以说I am a Chinese.和I am English. I am Chinese .nom student . I am good at Chinese. I LOVE china,I am chinese!