"Why is the sand for the garden still in the car?"
Translation:Hvorfor er sandet til haven stadig i bilen?
Think of it as the adverb comes after both the subject at the main verb, rather than just the verb alone. Here the subject is "sandet til haven" and the verb is "er" so whichever order they are in (either "Sandet til haven er..." or "Er sandet til haven...") the adverb always comes afterwards
Thank you for the explanation. It sounds like it might help me. Is there some resource about Danish word order in general? There sentences sprinkled through the tree which trip me up every time because more atomic rules come together and I have no idea how to combine them (question and adverb, question and negation, more clauses etc.).