The indefinite article is under-, the definite article is overused in Hungarian compared to English. You can mostly omit "egy", it's implied here but you could also say "Ő egy diák vagy egy tanár?" in this case, it would be natural, other times using "egy" would mean emphasis.
Ok here's a situation that doesn't translate well. The sentence seems to imply that someone in a school is acting like a teacher, but it's assumed he/she is a student. Someone comes along and sees the student acting like a teacher and asks, "Is he a student or the teacher?"
That's what I put, and I stand by it. Is he a student or teacher is also right, but when it marked me "wrong" it said I should have said "Is he a student or a teacher." That seems unnatural to me.
I saw it more like 'they're at X college', 'oh, are they a student or a teacher?'
WHY CAN'T I USE GENDER NEUTRAL PRONOUNS IN ENGLISH??? Ok, It's out of my system, but "Ő" literally translated to singular 'they'. I know that they don't like this as an answer because there is a different word for the plural 'they' in Hungarian, but it is perfectly grammatically correct to say "are they a student or teacher"... I'll just keep reporting anything that doesn't accept 'they' for 'Ő'...