because of adjective decinlation.
- Der Bär
- Der langsame Bär
- Ein Bär
- Ein langsamer Bär
With indefinit articles the adjectives take the ending matching the definit article
- Der Hase | Die Schlange | Das Pferd
- Ein kleiner Hase
- Eine kleine Schlange
- Ein langsames Pferd
He is a slower bear = Er ist ein langsamerer Bär (I know it is awkward to pronounce and to spell)
"Slower" is an adjective, and you can't use an adjective to modify a verb (not in proper English, anyway, despite how common it might be in colloquial English). So instead of "slower" you would have to say "more slowly". And while not incorrect by any means, there is also the small issue that "all" is not as common as "everything" and sounds a little bit stilted outside of preset constructions ("If all goes well...").
Ah, but on that logic, the exemplar answer is wrong too. "Everything goes slower." I agree, I would say "more slowly" in actual conversation. But I take DuoLingo on its own terms and the adverb / adjective difference does not seem to be what's going on here.
The whole adverb / adjective thing gets a bit murky for me translating back and forth between English and German. English adverbs usually differ from the adjective forms where the German ones often do not. So it makes sense to me to cut a little slack as to accepted forms unless the distinction is perfectly clear in a given instance.
Based again on the exemplar answer, they seem to be treating "slower" as a predicate adjective. It sounds clunky to me in English, but I can't say whether it is strictly wrong.
It's hard to tell if you're agreeing with me or disagreeing, because your written tone suggests that you disagree, but the content is all in accordance with what I believe. Yes, on that logic the exemplar answer /is/ wrong. Duo accepts colloquialisms, but that doesn't make them correct, which you seem to recognize already. I think "goes slower" is colloquial enough and enough people requested it to be an accepted answer that Duo has now accepted it. Heck, maybe they accepted it in the first place because of either coding, carelessness, or misunderstanding. Who knows? But in order for it to be a predicate adjective, however, you need a linking verb. "Goes" can be a linking verb in some instances where it means "becomes," (e.g. The apple goes bad.) but I can't think of an example where it would work with "goes slower," but maybe you can.
My students seem to have trouble with the adjective/adverb distinction, and they're all native English speakers. It's made even more complicated by the fact that you can't just ask, "Is the word describing the action or the subject?" because in many cases (like this one) it appears to be doing both. They have trouble learning it, and I have trouble describing how I know which one is proper. This is one case where German is a LOT simpler, and my students appreciate that. When they go from German to English, I don't take off points if they use an adjective instead of an adverb, as long as I can tell that they understand the underlying meaning. I'll leave it to their English teachers to correct their English grammar, especially for something that appears to be on its way out.
Anyway, I think I answered Matt's question correctly. I didn't intend to answer the question, "Why isn't Duo accepting my answer?" but rather, "Why is my answer not grammatically correct?" Maybe that's where the confusion came in, since he didn't specify. If I were answering the former, I'd say it's because of the word "all" being an unlikely candidate in this sentence. Hope that clears it up!
::edit:: Please read with a lighthearted tone. Some of my word choices appear to make this seem like I'm trying to argue (I'm bad at that), but I think we agree completely.
I wasn't agreeing or disagreeing with you actually. More musing on the maddening business of losing hearts when you full well know the correct answer, and noting DL can be inconsistent in its "logic". In the mostly binary world of DL, except for getting a pass on the occasional umlaut, you are fully right or fully wrong! Grrrr .... A couple of typos and and an adverb / adjective issue and you are starting over. Oh well, it's a useful tool anyway. Well worth the price. :-)
Does anyone besides me hear this as "Alles geht langsam an"? I miss it every time, which I guess shows that I'm a slow learner.
You can't reject my answer by typing "Everything goes slowly" because "more slowly" is grammatically incorrect in English. It is either "more something" or "somethingly", you can't have both.
I swear most answers I have are right but don't quite fit what the app wants to hear.