Voted Best Answer
May 06, 2014 - 12:55 PM
When the preposition "in" implies motion (e.g. going into some place), then the accusative is used. If the preposition implies location (e.g. being in someplace), then the dative used.
In all the examples you cite, the preposition "in" implies motion. In each example, someone is going into someplace, rather than just located there.
In all the examples you cite, the preposition "in" implies motion. In each example, someone is going into someplace, rather than just located there.