It was public knowledge that they were involved in criminal activities.众所周知，他们参与犯罪活动。Their affair is public knowledge.他俩的风流韵事已是尽人皆知。It was public knowledge that he was going to resign.他将要辞职是人尽皆知的事了。His legal problems are a matter of public knowledge.他的违法问题是人人皆知的事。