unbeknown
adj. 未知的，不为人知的
例句
Unbeknown to her they had organized a surprise party.
他们瞒着她筹备了一个给她意外惊喜的聚会。
《牛津词典》
It appears that unbeknown to Bolwell, the future (much like President Obama) has already arrived.
博尔·维尔可能不知道的是，这种未来(就像奥巴马一样)已经成为现实。
Unbeknown to them, the "scrap" contained a highly radioactive source used to treat cancer patients.
他们不知道这件“废品”里有一个用于治疗癌症患者的高辐射源。
