What is the role of only here? Its weird English sentence.
It emphasizes the adverbial phrase "very rarely." It's not merely that it's very rare, it's only very rare; there are never periods where it isn't rare.
What is the role of anything in this sentence, and a full stop after "...are they active". You can't tell if this is question or someone had too many beers.
what happened to the verb at second position
When does nur mean but? As in, where should it be placed?
nur never means but I believe
The hover hints give 'but' as a meaning.
I'm not too sure if what I said was correct. You should talk to a native
You could say, "They are active but very rarely" in English. In this case, "but" does have a meaning similar to "only". I imagine the German "nur" means "but" in this sort of situation.
only very rarely that they're active ?
only very rarely is she active? Couldn't this go either way: she or they???
sie IST aktiv = she is active
"Only very rarely are they active." This is the most senseless sentence I have ever heard.
"Only they are very rarely active." would have some sense as a second part of some complex sentence.