Translation:The Mongolian writer is sitting on the fiftieth chair.
I think this is among the better sentences in the Hungarian course.
I think that, for all we complain about the sentences sucking and being generally terrible, it might help to point out ones that are particularly effective - like this one, which is short and non-convoluted enough that inexperienced non-native speakers can get a handle on it. We should have more sentences like this.
Nearly the same problems with German. You can even sit on or in the bed. It depends, where you're feet are, on the ground or in the bed as well. And the softness of a sofa or armchair is important, whether we use on (like on a chair) or in (like in very soft furnitures). We usually translate our imagination of it, if we can't see it or the sentence of the other language is not clear enough. I don't know, how it is in Hungarian. It would be interesting. But anyway, it is quite difficult for beginners of so many different countries and more options should be valid.