Always accusative prepositions
Prepositions are little words that connect different parts of a sentence, like showing where something is or when it happens. In English, we do not have to worry about grammar cases after a preposition. In German, however, prepositions dictate the case of the noun or pronoun that follows.
Some German prepositions can take different cases depending on the context. However, a small, stubborn group of prepositions always demands the accusative case. The most common ones you will encounter are durch, gegen, ohne, and bis, along with words like für and um. Because English speakers often default to the dative case after prepositions, this group requires a little extra attention.
When you use an always-accusative preposition, the noun, pronoun, or article immediately following it must be in the accusative case. These prepositions do not care if a verb describes motion, location, or a state of being. Their rule is absolute: they just want the accusative.
As a reminder, the accusative case primarily changes masculine words. A masculine article like der becomes den, ein becomes einen, and a pronoun like er becomes ihn. Feminine, neuter, and plural words look exactly the same as they do in the basic nominative case.
Let us look at a few of the core members of this group in action. The preposition durch means across or through. You use it when moving from one side of a space to another.
The preposition gegen means against. You will use it when talking about a sports match, a physical collision, or a competition.
The preposition ohne means without. It is incredibly common in everyday German, and because it takes the accusative, a masculine pronoun like er will always become ihn.
The word bis usually means until. It firmly belongs to this accusative group, but it behaves a bit differently. Most of the time, bis is used with time expressions where the accusative case is clearly visible on the adjectives.
When you want to use bis to talk about a physical destination, it rarely works as a standalone preposition. Instead, it teams up with a second preposition, most often zu. When this happens, the second preposition takes over and decides the case. Because zu always forces the dative case, the noun will end up in the dative case.
Also, keep in mind that bis can sometimes be used to introduce a completely new part of a sentence, acting as a connecting word rather than a preposition.
To master these prepositions, memorize the core set: durch, für, gegen, ohne, um, and bis. Whenever you use them as prepositions, follow them immediately with the accusative case, paying special attention to how masculine nouns and pronouns change.