"Are those our oranges?"
Translation:Sind das unsere Orangen?
In German we usually just use the singular neuter pronoun when introducing something, regardless of gender and number of the introduced thing: „Das/dies sind Orangen.” And the same is true when forming the corresponding question.
I wrote "Sind die unsere Orangen" and got marked wrong. Could that also be correct though?
That would be the plural which is at the very least highly unnatural.
I tried "Sind dies unsere Orangen?" and it was marked incorrect. Is it?
Yes. Your sentence would mean: “Are these our oranges.” (rather than “those”).
Does generally the following translation hold true? (dies => this / these) (das => that / those)
I’m not sure if it’s officially wrong, but it’s at the very least be very unnatural. We usually just use das when identifying something (or asking the other person to identify it) like this, regardless of gender and number.