Quote Originally Posted by xXHoax View Post
I'm just starting to wonder if it's the site that's wrong.

Advanced level exercises: Nouns and cases (17)
Site is correct. I took 8/10 (mistake 1: pro + ???, v sadax: unjustified mistake).
Indeed some of the constructions are confusing for foreigners learning Russian.
But there are reasonable explanations.
Some times predlozhnyi padezh is expressed with this ending: v sadu, v shkafu, v lesu etc.
Also sometimes in order to indicate period of time Russians use Tvoritel'nyi padezh: utrom, zimoi, letom, vesnoi etc. And this might be confusing in understanding the general meaning. For this reason you did minor mistakes.
Also some words indicating quantity require the use of Roditel'nyi padezh e.g. bolshe, menshe etc
Finally some standardized constructions: Mne veselo/grustno.

Keep the effort!