Learn Hardcore German: Ich schließe den Drucker an den Computer an.

One an is the preposition meaning “to” or “toward,” which introduces the phrase an den Computer. The second an is the separable prefix of the verb anschließen, which detaches from the verb stem and goes to the end in a main clause.

What rule makes the prefix an go to the end of the sentence?

anschließen is a separable‐prefix verb (Trennbares Verb). In German main clauses, the verb stem (here schließe) stays in second position and the prefix (an-) moves to the very end of the clause.

Why is den Drucker in the accusative case?

anschließen takes a direct object—what you are connecting—which is always in the accusative. den Drucker answers the question “What am I connecting?”

Why is an den Computer also accusative, not dative?

an is a two-way preposition (Wechselpräposition). When it expresses movement toward something, it governs the accusative. Since you are moving/connecting the printer onto the computer, you use accusative (den Computer). If it were a static location (“on the computer”), you would use dative (am Computer).

Why does schließe use ß instead of ss?

The base verb is schließen, spelled with ß after the long vowel ie. In the first-person singular present tense, the stem remains schließ- and takes -e, giving ich schließe. The ß signals the long vowel.

Can I use verbinden instead of anschließen? What’s the difference?

Yes. You could say Ich verbinde den Drucker mit dem Computer.

anschließen (separable) often emphasizes the physical act of plugging in or attaching a device.
verbinden (inseparable) is more general and uses mit + dative. It can be used for both physical and abstract connections.

What is a separable‐prefix verb and how can I recognize others like anschließen?

A separable‐prefix verb has a prefix (e.g. an-, aus-, zu-, mit-) that detaches in main clauses. You can often spot them in the infinitive: dictionaries list them as anschließen, ausgehen, zumachen, mitbringen, etc. If the prefix carries the main stress in the infinitive, it’s usually separable. In sentences, you’ll see the prefix at the end when you conjugate the verb.