I am a Chinese girl.为什么不用:I am an Chinese girl.

I am a China girl还是Chinese I am a Chinese girl.为什么不用:I am an Chinese girl. i am a chinese girl 用she改写 i want to make friend with forieners.i am a chinese and i am 18.i am a girl who can help me to have a english name .chinese name张璐锋i am a girl i am proud i am a chinese i am a girl from I am a girl feom I am a pretty girl i.am.a.good.girl I am a girl 歌词 i am a sweet girl 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 Hello...I come from Birmingham.My family wanted me to find a Chinese girl as a friend.I am a girl I am a Chinese girl.(用she改写) the,pen,is,a,there,on,desk.(连词成句) 英语：I am a Chinese girl who like country music and delicious food.这句话有没有语法错误 I am a Chinese和I am Chinese哪个对?我老师说“I am a Chinese 是错误的句子,除非在后面加boy或girl才对”,但我看的课外书上却有I am a Chinese.