"They secure the room."
Translation:Sie sichern den Raum.
Is the word "Raum" used for "room" in the general meaning only (space, area) or can you use it also as a synonym for "Zimmer" (a room in a building)?
It can mean all of them. If you're referring to your own room, always use "Zimmer", though. "I go to my room= Ich gehe in mein Zimmer". "Ich gehe in meinen Raum" is not idiomatic.
But then it looks like that the German and English sentences do not match.
- They secure the room >> Sie sichern das Zimmer;
- Sie sichern den Raum >> They secure the area.
Did I miss something?
Yes, you missed the own :) It's not idiomatic with the possessive, otherwise it's fine. Both of "Sie sichern den Raum/das Zimmer" mean "they secure the room".
What is about "Sie stellen den Raum sicher"? The program says its wrong, but I can't see a mistake.
how about 'sie versichern den Raum' i suppose this technically means 'they insure the room', but should it be accepted?
No sorry but I don't think it should be accepted. Secure/sichern and insure/versichern are completly different things.