"Who" as a question?

[Wesam]

Who as a question.
If the sentence just like this-
She has been studying French for three months.
Can we make a question using "Who" if not .how can we make a question about this sentence.
I hope you will answer as soon as you can .

[Milanya]

Who has been studying French for three months?
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con·text - The part of a text or statement that surrounds a particular word or passage and determines its meaning.

[Wesam]

but how if we don`t know -Who ?

[Wesam]

my friend asked his students to make a question about this sentence and my co ordinator asked me about this-If he can use Who?.Because of that I want to be sure about it`s use.There was no text but a sentence

[Kitosdad]

Wesam, Milanya has answered your question in the only possible way without further text.

" I've been told that one of the female members of this class has been studying French for three months", said the teacher. " Who "?. ( I can construct this scenario, but ..... )
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Keep it simple ... Keep it interesting.