Learn Danish: Forventer du at de aldrig sover? - Do you expect that they never sleep?

You are right! In a main clause, the adverb aldrig (never) comes after the verb (De sover aldrig). However, at de aldrig sover is a subordinate clause (a clause that cannot stand alone). In Danish subordinate clauses, central adverbs like aldrig, altid (always), and ikke (not) must be placed before the verb.

Can I drop the word at like we often drop the word 'that' in English?

Yes, just like in English (Do you expect they never sleep?), you can often drop at in Danish when it connects a main clause to a subordinate clause. Saying Forventer du de aldrig sover? is perfectly normal in everyday Danish.

Why does the sentence start with the verb Forventer instead of Du?

Because it is a yes/no question. Danish yes/no questions swap the subject and the verb. Instead of the normal subject-verb order (Du forventer = You expect), it flips to verb-subject (Forventer du = Do you expect).

If I change the first part to a statement, does the word order in the second part stay the same?

Yes! The rule for subordinate clauses applies no matter what the main clause does. If you say Jeg forventer at de aldrig sover (I expect that they never sleep), the adverb aldrig still stays firmly in front of the verb sover.