"What kinds of buildings does János like, tall ones?"
Translation:János milyen épületeket szeret, magasakat?
why not "milyen épületek jános szeret, magasakat?" is it because you have to lead in with the subject?
You don't have to start with the subject, but in this case it can't separate the verb and the object, so the only other possibility is: "Milyen épületeket szeret János?"
(Note: épületek is in accusative, so it becomes épületeket.)
Because, in Hungarian, adjectives that modify a noun stay singular, even if the noun is plural. Similar to English:
red buildings - piros épületek
Here, the question word "milyen" is in a similar role, so it also stays singular.
I think I've got the idea, but maybe your explanation should be somehow corrected a little. "Milyen" isn't an adjective, I believe it's a pronoun. And we know pronouns behave different ("ezeket épületek").
That is exactly why I said it is in a similar role, and not that it is an adjective. Let's say it is a question word, the answer to which is an adjective. In Hungarian, it is a "melléknévi kérdő névmás". So that is kind of a "place holder" for an adjective. Hence, it behaves like an adjective.
On a side note, "ezeket épületek" is incorrect. It is either "ezek az épületek" or "ezeket az épületeket". "Ezek" is a demonstrative pronoun, which indeed behaves very differently.
In the next task I saw "Milyeneket keresel, alacsonyakat vagy magasakat?". I am totally confused.
Continuing on my previous comment, this is the next step. Let's first look at a real adjective with a noun:
"Magas épületek" - tall buildings.
What happens if we take away the noun? The English language uses the place holder word "one" in that case: "tall ones". As in:
What kinds of buildings? Tall ones.
Hungarian, on the other hand, doesn't need a place holder. And that is because, in Hungarian, the adjective itself can act like a noun.
"Milyen épületek? Magasak."
And if the noun had some suffix(es), then, on taking away the noun, the adjective will "inherit" its suffixes:
"Milyen épületeket? Magasakat."
And the same thing can happen with the "melléknévi kérdő névmás", the question word that asks for an adjective. That is how
"Milyen épületeket?" becomes "Milyeneket?"