Explain why "Who is she playing the piano?" is incorrect?

Question

A teacher asked me this question and I am having a hard time finding a simple way to explain it for her to share with her students. I`m looking for the easiest way to explain it to her because she teaches Junior High School English in Japan. The students were given a picture prompt and expected to answer with, > "Who is the girl playing the piano?"Many of the students wrote, > "Who is she playing the piano?"How would I explain, in a very simple way, why you cannot use **she** here? Thank you so much for your help!

Answer 1

Hi there,

Basically, you are inserting a second subject by adding "she". The question word "who" already denotes that we are asking about a subject, therefore another pronoun violates English's basic rule of Subject + Verb + Object

Hope that helps!

Answer 2

I would just put a comma after “she” and have “playing the piano” modify “she.”