"The American airplane lands in this German city."
Translation:Az amerikai repülőgép leszáll ebben a német városban.
You used different endings (suffixes): ebBEN a városBAN is correct with the verb leszáll. The preverb "Ie" made a new word: száll-flies, leszáll-lands. We would say: ebBE a värosBA repül, because repül is a motion wich can have a direction.
I translated the end of this as "...ebben a német városba" which was rejected. I was assuming that the plane is entering the city (from above) as it lands, so I thought -ba would be the right choice. I guess the implication here is that the plane is already in the city as it lands? I'm not even sure what difference it makes.