no, they are in the corn field
This one was hilarious.
Since "au" was used, my translation was "have disappeared" and was accepted per DL.
DL accepts both Past Simple and Present Perfect in most of these exercises. In several Romance languages, e.g. French and Italian, the grammatical equivalent of the Present Perfect is used for both functions, at least in the spoken language.
Not just Romance languages. German does it too. Well actually at least in French and German the simple past exist and are I believe still used in writing, but not in the spoken languages.
There's an interesting litte paragraph on the Romanian Simple Past here:
This perfect form is always translated inte english preteritum "disappeared". Can it also mean "Michael and Mary has disappeared" or is there another (commonly used) form for that in Romanian?