Der Teppich im Flur muss gewechselt werden.

The carpet in the hallway must be changed.

Breakdown of Der Teppich im Flur muss gewechselt werden.

• in: in
• dem: the; (masculine or neuter, dative)
• müssen: must
• der Teppich: the carpet
• der Flur: the hallway
• gewechselt werden: to be changed

Questions & Answers about Der Teppich im Flur muss gewechselt werden.

Why is im used in im Flur instead of writing in dem Flur?

im is a contraction of in dem, commonly used before masculine and neuter nouns in the dative case. So im Flur = in dem Flur (in the hallway), but im is shorter and more idiomatic.

Why is Teppich the subject (nominative) when it sounds like the object in English?

Because the sentence is in the passive voice. In an active sentence like Man muss den Teppich im Flur wechseln (“One must change the carpet in the hallway”), den Teppich is the accusative object. In passive, that object becomes the subject, taking the nominative form Der Teppich.

What role does werden play in gewechselt werden?

In German passive constructions, werden is the auxiliary verb. With a modal verb (here muss), you combine the past participle (gewechselt) with werden at the end:
• muss (modal)
• gewechselt werden (participle + passive auxiliary)
This yields “must be changed.”

Why is the past participle gewechselt placed before werden, and why are both verbs at the end?

In a main clause with a modal verb, the finite verb (muss) goes to the second position. All non-finite verbs (the past participle gewechselt and the infinitive werden) move to the final position. The order is participle first, then the auxiliary: …gewechselt werden.

Could you show me the active equivalent of this passive sentence?

Yes. The active form is:
Man muss den Teppich im Flur wechseln.
Here man is the impersonal subject, muss the modal, and wechseln the main verb.

Why is Der used instead of Den for Teppich in Der Teppich?

Because in the passive voice Teppich is the subject and subjects take the nominative case. The nominative masculine article is der. In the active sentence the same noun is the object (accusative) and would take den.

Why is Flur capitalized in im Flur?

All German nouns are capitalized, regardless of their position in a sentence. Flur (“hallway”) is a noun, so it always begins with a capital letter.

Can I use ausgetauscht instead of gewechselt? What’s the difference?

Yes. You can say Der Teppich im Flur muss ausgetauscht werden. Both gewechselt and ausgetauscht mean “changed” or “replaced” here. ausgetauscht often emphasizes that the old item is taken away and a new (or similar) one is put in its place, while gewechselt is slightly more general.