"Professorn behöll nyckeln."
Translation:The professor kept the key.
Occasionally Duolingo will want to teach you more words than it has space for within a single lesson. It decides you've seen all of them and moves on even though you never learned one or two. It's a rare occurrence, and I'm not saying that's conclusively what happened, but it's possible. Or maybe you just missed it - who knows? :)
It's not a problem if a new word comes up in an exercise. We can always search it in a dictionary or on internet if we don't understand something. That's what learning languages is all about. We can't always get everything "served on the table." :)
Wouldn't "The professor held the key" work here as well?
No, behålla means keep as in not giving back, not as in having in one's hands.
I guess I meant "The professor held onto the key" in that sense. No?
Was missing, but that's fine by my. I've added it now. :)