Questions & Answers about Wir steigen in den Zug.
The preposition in can take either the accusative or the dative case, depending on the meaning:
- Accusative (movement → where to?): going into/onto something
- Dative (location → where?): being inside/on something
In Wir steigen in den Zug, you have movement into the train, so you ask:
- Wohin steigen wir? – In den Zug. → accusative
That’s why it is den Zug (accusative masculine) instead of dem Zug (dative masculine).
Zug is a masculine noun:
- Nominative: der Zug
- Accusative: den Zug
Because of the preposition in with movement (see previous answer), you need the accusative. So:
- Subject (doing the action): Der Zug fährt. – The train is going.
- Object with movement into it: Wir steigen in den Zug. – We get on the train.
So den is simply the accusative form of der for masculine nouns.