以下只是就原文做出的修改：
This story（既然是story,就应该全部用过去时.） is about a high school girl,called Miya.
She（建议用Miya） is（was） a girl,who has（had） a mother but no father.
She is（was） so common(common形容人不是很好,建议用ordinary) in his（应该是her） class that （建议加上even） her teachers can't（didn’t,不应该用can’t） know her name.
All of a sudden,when（when应该接过去时） she is（所以应该用was） told that she is（was） a princess of another country---the future successor ,she is（was） more than pleased.
And then,she becomes（became） a focus in media.
However,after all,（这两个词其实意思上重复,建议去掉after all）she was brought up in a poor family,and（brought up in a poor family和had no elegant royal quality并不是并列关系,而是因果关系,建议：For the reason that she was was brought up in a poor family,she had no elegant royal quality.） she has（had） no elegant royal qualities（既然前面用no,这里应该用单数quality）.
To train her to own these（these指代不明,前文根本没有提及指的是什么,应该用some） （建议加上elegant,因为上文有提及）royal qualities,her grandmother spent（spend） great efforts on her .
In her （her指代不明,应该用her grandmother’s） training,she would like to give up this （应该用the,this指代不明）position as princess（a princess 因为下面是a princess,而且也应该加a） ,so she faces（faced） a decision （face a decision?搭配不当.应该用face a problem）whether to be a princess or not.
