Learn Hardcore German: Ich lese ein Buch über den Hund.

In German, Hund is a masculine noun. When it follows a two‐way preposition like über, which here indicates what the book is about, the accusative case is required. In the accusative, the masculine definite article changes from der to den.

What case does the preposition über take in this sentence, and how do I know?

In this sentence, über takes the accusative case because it describes the subject matter of the book (“about the dog”). Although über belongs to a group of two‐way (Wechsel‑) prepositions that can take either the accusative or dative depending on context (direction versus location), when expressing the topic of content—as in “a book about something”—the accusative is used.

What is the function of the verb lese and what tense is it?

Lese is the first-person singular form of the verb lesen, which means “to read.” It is in the simple present tense, indicating that the subject, Ich (“I”), is performing the action of reading, either as a current action or a habitual one.

How does noun gender affect the articles in the phrases ein Buch and den Hund?