Breakdown of Als er brand is, moet je de brandweer bellen.
zijn
to be
bellen
to call
moeten
to have to, must
er
there (existential)
Questions & Answers about Als er brand is, moet je de brandweer bellen.
Why is the verb is at the end of the first part?
The word als (if/when) introduces a dependent clause. In Dutch, these types of words always push the conjugated verb—in this case, is—to the very end of that clause before the comma.
Why does the second half say moet je instead of je moet?
In Dutch main clauses, the verb almost always takes the second position. Here, the entire first clause (Als er brand is) counts as position number one. So, the verb moet must come immediately after the comma, which pushes the subject je to the other side of the verb.
What does er do in this sentence?
Together with is, it forms er is, which means "there is". Just like in English, you wouldn't say "If fire is," you say "If there is a fire." Because als pushes the verb to the end, er and is get split up by the word brand (fire).
Why is bellen (to call) at the very end of the sentence?
The second half of the sentence uses the helper verb moet (must). When you use a modal helper verb like this, the main action verb in its full infinitive form (bellen) always gets sent to the very end of the sentence.