I am in confused that When I ask to unknown person, then how to ask: Who are you? or Who you are..
Other examples:
What is he doing? or what he is doing..
How are you? or how you are..
What is the reason behind that? In which condition we use them separately ?
Best Answer
The above is a question. It employs an inverted structure so that the listener knows it's a question. By "inverted structure," I mean that it places the primary subject of the noun "are" after the verb. Uninverted, it would be: "You are who?" "Who" appears in the question—no matter how it's stated—as a second subject, as part of the predicate, specifically the predicate nominative.
The above is a clause, always appearing as all or part of a noun clause. As such, it only appears as part of a larger sentence, for example: