I. Theory
In German, each preposition governs a case. However, there are certain commonly used prepositions that can govern either the accusative or the dative depending on their function in the sentence. For the most part, this is when these prepositions are conveying movement or a lack of movement. In English, since we don’t use cases to show this nuance, we have modified prepositions:| Ich gehe ins (in das) Haus (accusative). I go into the house. but Ich bin im (in dem) Haus (dative). I am in the house. *Wir fahren hinter die Berge. (accusative) We drive behind the mountains. but *Die Stadt liegt hinter den Bergen (dative). The city lies behind the mountains. |
* In these examples, we see no distinction in English. However, in the example below, we see that the German tells us more than the English: