Why aren't de her, den her, det her, de der, den der, and det der accepted for this/that?
I've seen them used on some Danish sites and I know what they mean because of my friend learning Swedish and some other resources.
edit for those who do not know:
de her - these. det/den her - this. de der - those. det/den der - that.
I'm not 100% (this is my first time doing Danish in yeeears) but I think it's because her/der add units of meaning similar to 'here/there' so for a general sense of 'this' or 'that' they may be too exact... but that's just a guess, and I tried using det der (etc) a few times and it was marked as wrong.
I'm not 100% sure why they aren't accepted, seeing as I wasn't around when the course was being created, but I imagine it's because it's maybe a bit more advanced and only "denne/dette/disse" and "den/det/de" are introduced in the course (though "den/det/de her" I believe is introduced later in the course), however I believe it's slowly being added to some more and more sentences as acceptable alternatives, but if they're not accepted, remember to report it using the "Report a Problem" button and hopefully one of us will be able to add it
I have discovered something that I is helpful with my sanity in using Duolingo Danish. Remember that Duolingo is a resource pushed to the "good enough" level rather quickly by volunteers (that would be wonderful volunteers), The system seems to be that, after having what we might call the "A team" of volunteers get it to that good enough level, the rest of us become a "B team" whose job is to assist with the polishing by suggesting such things as you do here and to cheer on those working on the continuing development. This "B team" function is especially important regarding thinking of all possible acceptable alternate translations. If you want to check something like this most quickly and don't have a Dane to consult, I suggest the Duolingo Danish group on Slack. In the question section there is always a discussion of something like this going on. So, yesterday, for example, someone posted a question about the difference between "bare" and "kun" and got an answer within the hour.