Quote Originally Posted by George1992 View Post
Hi friends!

I asked a question on WordReference forum and I don't know which answer(s) I'm supposed to choose. Do you agree with some of them? Which one(s) exactly?

Сложившееся мнение | WordReference Forums

I don't understand only сложившееся.
I would go for Sobakus's opinion:
"...Thus, "сложившееся|распространён ное|бытующее мнение|убеждение" are all completely interchangeable in journalistic context and correspond perfectly well to En. "popular belief".

Cложившееся comes from the verb "сложиться" in the meaning "принять определенное положение, вид,форму"- to take a particular shape. Cложившееся- something that has taken a particular shape.
It has nothing to do with "to be put together" in this case.