I'll do my best to explain, though I'm not a native speaker. In a natural sounding sentence, the adverb comes just before the verb, such as in "Az alma bent van."

This order can be disrupted by what is called a focus word. Focus words include:

• negation (nem, nincs, nincsenek)

• questions, (ki? mi? hol?)

• answers to questions

• and any stressed or emphasized word.

If a sentence contains a focus word, that word must be placed immediately before the verb- consequently "kicking out" what would normally be there to a position immediately after the verb. In this case, we would say, "Az alma bent van," but what if we didn't know what was inside? We would have to ask what's inside, and questions are considered focus words, so now the question word "mi" takes the position just before the verb, and kicks out what would normally be there (the adverb) to a position after it.

Thus we get:

1. Mi van bent?

2. Az alma bent van

I hope this helps. Let me me know if it doesn't make sense.

Yes, maybe it's the hardest thing in Hungarian (most of the questions are about word order). And sorry, but I don't know why it is incorrect (but it is), maybe someone else can explain it.