"Peter does not run up to Kathy, only walks up."
Translation:Péter nem felfut Katihoz, csak felsétál.
I thought the prefix had to separate when the verb is negated - especially since it's not the fel- that's being negated here, but the fut. Is it not so?
It is the whole thing, "felfut". It is denied and an alternative is offered:
"Felsétál" instead of "felfut".
The other way is when it is more of a yes/no situation, nothing more:
Does he or does he not run up?
"Felfut vagy nem fut fel?"
"Nem fut fel" is simply the negation of the statement: "Felfut".
You can think of the other one as this: the action performed is not "running up" but "walking up". Nem felfut, hanem felsétál.
I keep giving Kati a definite article because it's already kind of muscle memory to do that with objects in this course.
Sorry for objectifying you, Kati. :c