Translation:The pet disappeared the day before yesterday.
You can never use the present perfect ("has disappeared") in English, when referring to a specific time ("the day before yesterday").
Why wouldn't this use "had disappeared"? I see this inconsistency of translation in a few of these past tense excercises. It seems arbitrary to me.
Why would it be had disappeared (Past Perfect)? The Dutch version of had disappeared is was verdwenen.
Eric, there is no inconsistency in the DL exercises on this point.
The English simple past can be translated into the Dutch simple past or into the Dutch present perfect (has disappeared), but not into the Dutch past perfect (had disappeared).
Conversely, a Dutch sentence in the present perfect can often be translated into either the English present perfect or the English simple past (but not the past perfect).
If the sentence is about a specific point in time in the past (e.g., yesterday), then the English simple past, not the present perfect, must be used.