He went there unbeknown to me.
他瞒着我到那里去的.
《现代英汉综合大词典》
I am appalled that children can mount up debts unbeknown to their parents.
让我深感震惊的是，孩子们竟会背着父母欠债累累。
柯林斯例句
His past is ancient and unbeknown just like his true power.
他的过去古老而不为人知,就如同他的真实力量一般.
互联网
He did it unbeknown to us.
他瞒着我们做了那事.
互联网
He did it unbeknown to me.
他瞒着我干那件事.
互联网
"a crisis unbeknown to me"
"she had been ill for months, unbeknownst to the family"
"unbeknownst to me, she made all the arrangements"