open secret 公开的秘密

英文释义

Something that everyone knows, but that is supposed to be a secret.

例句

Since they have been in love since being in high school together, it's an open secret that my sister is going to marry my best friend.

我妹妹打算和我最好的朋友结婚，这已经是公开的秘密，因为他们在上高中时一直在谈恋爱。