"I need a bit of sugar."
Translation:Jeg behøver en smule sukker.
From Palmwknfbpa's comment here https://forum.duolingo.com/comment/5731948?comment_id=32976919:
That one is difficult, but no, you can't say "en smule af sukker." It sounds wrong in Danish. "En smule sukker" is the right pronouncation. :)
It still does not explain why, but at least says "calm down, that's how things are" :) So I'll leave it here, for in this tread there's no answer at all...
BTW, I thought Duo has same discussion thread, no matter the direction of the translation... but looks like it's not always true :)