"I am never going to allow that."
Translation:Det kommer jag aldrig att tillåta.
In the reverse Swedish -> English [translation] (https://forum.duolingo.com/comment/11107081/), Arnauti had the same issue:
"The kommer/ska thing is very subtle in this case, I don't think I can explain it, at least not off the top of my head. ska would somehow put too much intent into it here. It's very much about wanting or not wanting something to happen. It could also be something about the time frame. Maybe others have better ideas."
So, with two excellent translators having issues, it must be difficult :)
A Google search of "det ska jag aldrig att tillåta" does give some hits, but not so many. The whole list:
- "Du ska aldrig tillåta att nån tilltalar dig så. ALDRIG." [Sounds like a command.]
- "5 saker du inte ska tillåta i ett förhållande" [Again, telling you what to do.]
- "...för att jag räddar honom, så skall jag aldrig tillåta någon annan än mig sjelf, att betala penningarne." [From 1844!]
My (probably incorrect) conclusion: you use "ska" in this case to make it more or less as a command. At least in the last 100 years or so :). I'd love your feedback develanteriel!