Breakdown of Die Möbel müssen montiert werden, bevor das Zimmer eingerichtet werden kann.
das Zimmer
the room
können
can / to be able to
müssen
to have to, must
bevor
before
Questions & Answers about Die Möbel müssen montiert werden, bevor das Zimmer eingerichtet werden kann.
How do we form the passive voice with a modal verb in the first part of this sentence?
You put the conjugated modal verb (müssen) in the second position, just like in an active sentence. Then, the action being done goes at the very end as a past participle (montiert), immediately followed by the infinitive werden (to be).
Why does the second part end with three verbs in a row: eingerichtet werden kann?
The conjunction bevor creates a subordinate clause, which forces the conjugated verb (kann) to the very end of the sentence. Right before it sits the passive structure we saw in the first half: the past participle (eingerichtet) plus werden.
Why is the plural verb müssen used with Möbel, when "furniture" is singular in English?
In English, "furniture" is an uncountable singular noun. However, in German, Möbel is a plural noun. If you want to talk about a single piece of furniture, you have to use the singular compound noun das Möbelstück.
Why does eingerichtet have -ge- in the middle, while montiert has no ge- at all?
einrichten is a separable verb, so the -ge- is placed between the separable prefix (ein-) and the verb stem. On the other hand, montieren ends in -ieren. Verbs ending in -ieren are an exception and never take a ge- prefix in their past participle form.