Two-way Prepositions Genitive Prepositions are used in prepositional phrases. These phrases consist of the preposition and the object of the preposition. A prepositional phrase usually answers the question of when, where, or how. In German, the preposition determines what case the object takes.
Most prepositions take either one or two cases.
Accusative These six prepositions are exclusively accusative prepostions. These nine prepositions are exclusively dative prepositions. Generally the rule if the preposition indicates motion, it is accusative. If the preposition implies location, it is dative.