Questions & Answers about Ich streite mit meinem Mitbewohner über den Müll.
Why are there two different prepositions, mit and über, used with streite here?
The verb streiten (to argue) pairs with specific prepositions depending on what you want to express. You use mit for the person you are arguing with, and über for the topic you are arguing about. Memorizing these verb-preposition combinations is a key part of learning German.
Why is it meinem with an -em at the end?
The preposition mit always forces the following noun into the dative case. Since Mitbewohner is a masculine noun, the possessive word mein takes the masculine dative ending, becoming meinem. While your current lesson covers possessive pronouns that completely replace nouns, here meinem is acting as a normal determiner attached directly to its noun.
Why do we say über den Müll and not über dem Müll?
über is a two-way preposition. When describing a physical location, it can take the dative or accusative case. However, when über is used abstractly to mean about a topic, it always takes the accusative case. Since Müll is a masculine noun, we use the accusative article den.
How is the word Mitbewohner put together?