Dative and accusative prepositions
Some prepositions take either dative or accusative objects, depending on the context of the sentence. When using prepositions such as an, auf, hinter, in, neben, unter, über, vor, and zwischen, you must determine whether the object following the preposition is meant to describe a static location, or meant to describe direction or motion toward a location or thing.
If it is describing direction and motion, the accusative case is used. Otherwise, the dative case is used. For example, the sentence "Put the bag under the desk" involves direction and motion. "The bag is sitting under the desk" describes a static location.
These exercises will help you understand dative and accusative prepositions. Only one of the four answers will work correctly with both the grammar and the content of the sentence.