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Questions & Answers about Ich pumpe den Reifen auf.
Why does auf appear at the end of the sentence instead of after the verb?
Because aufpumpen is a separable-prefix verb in German. In main clauses the prefix auf splits off from the base verb pumpen and moves to the end. The finite part (pumpe) remains in the second position.
What is the infinitive form of the verb used here?
The infinitive is aufpumpen, which combines pumpen (to pump) with the separable prefix auf.
Why is den Reifen in the accusative case and not der Reifen?
Reifen is masculine (nominative der Reifen). As the direct object of aufpumpen, it takes the accusative. The masculine article der changes to den in the accusative.
How would you say this sentence in the perfect tense?
Use haben + past participle. It becomes:
Ich habe den Reifen aufgepumpt.
The past participle of aufpumpen is aufgepumpt.
How do you replace den Reifen with a pronoun?
You swap the masculine accusative noun with ihn. So the sentence is:
Ich pumpe ihn auf.
What’s the difference between aufpumpen and aufblasen?
aufpumpen usually implies using a pump or compressor (e.g. for bike tires). aufblasen is more general “to inflate” (balloons, inflatable toys) either by blowing or with a pump. For a tire, aufpumpen is the more natural choice.
How do you form a yes/no question from this sentence?
Move the finite verb to first position and follow with the subject:
Pumpst du den Reifen auf?
Can I put den Reifen at the beginning for emphasis?
Yes. German still requires the finite verb in second position, so you get:
Den Reifen pumpe ich auf.
This fronting emphasizes den Reifen.