it is well-known that,还是it is well known that到底是哪一个?well known和 well-known有什么区别？

Question

it is well-known that,还是it is well known that
到底是哪一个?well known和 well-known有什么区别？

Answer 1

后者
it is well known that...是一种普遍用法,意思为“.是众所周知的”