英语短语"be deceived in sb."的核心含义是"对某人判断错误；看错某人；误以为某人具备某种品质/特点，结果实际并非如此"。它强调认知上的偏差——即说话者原本对某人有正面或特定的期待，最终发现这种期待是错误的（被"误导"了对某人的看法）。
"deceive"本身是"欺骗"，但"be deceived in sb."并非直接指"被某人欺骗"（那是"be deceived by sb."），而是"在对某人的认知上被（自己的判断）欺骗了"，即"看错了某人"。
主语：通常是"看错某人的人"（即产生错误判断的一方）；
谓语："be deceived"（被动语态，强调"被误导"的状态）；
介词搭配："in sb."表示"针对某人的（判断）"。
用于发现某人真实品质/能力与之前认知不符的场景，比如：
原本认为某人"诚实"，结果发现其"虚伪"；
原本觉得某人"可靠"，结果发现其"背叛"；
原本相信某人"有能力"，结果发现其"无能"。
通过例句更直观理解：
1、 I thought he was a trustworthy friend, but I was completely deceived in him.
我以为他是个值得信赖的朋友，但我完全看错他了。
2、 She was deceived in her partner—he had been lying about his job the whole time.
她看错了伴侣——他一直对自己的工作撒谎。
3、 We were all deceived in the new manager; he turned out to be lazy and unprofessional.
我们都看错了新来的经理——他其实懒惰又不专业。
4、 Don’t be deceived in him just because he’s polite; he’s actually very selfish.
别因为他有礼貌就看错他——他其实很自私。
注意区分"be deceived in sb."和"be deceived by sb."：
be deceived by sb.：被某人主动欺骗（强调对方的欺骗行为），比如：
He was deceived by his colleague into investing all his savings.（他被同事骗得投了所有积蓄。）
be deceived in sb.：对某人判断错误（强调自己的认知偏差），比如：
He was deceived in his colleague—he never thought the colleague would betray him.（他看错了同事——从没想过对方会背叛。）
"be deceived in sb."是表达"看错人"的地道说法，聚焦认知层面的失望，而非对方的主动欺骗。当你发现某人"名不副实"时，就可以用这个短语~