原因不明的死亡是难以接受的。

An unexplained death is difficult to come to terms with.

《柯林斯英汉双解大词典》

此文件摘自来源不明的联邦调查局档案。

The document was excerpted from an unidentified FBI file.

《牛津词典》

凯瑟琳找到了一封来源不明的空白信封。

Catherine found a blank, unidentified envelope.

youdao

The experience of having language speak through him and do things that he doesn't understand makes him want to acquire again that agency that he experienced when he took his father's words literally.

理查对自己所处的状态一无所知,说什么做什么都不明就里,这时的他渴望回到遵从父亲时期的状态,找回那种极富技巧的沟通方式。

耶鲁公开课 - 1945年后的美国小说课程节选

So, studies with police officers using reaction time in split-second choices on who to shoot find that your stereotypical attitudes play a huge role in who you're likely to shoot when they're holding an object in their hand that's unclear.

一些针对警察的研究,用霎间的反应时间让他们作出选择,应该向谁开枪，研究发现这些刻板态度,能极大的影响你选择向谁开枪,当他们手里拿着不明物体时。

耶鲁公开课 - 心理学导论课程节选

There's never been any agreement, so far as I can tell, as to who it is we're supposed to be imagining the outside observer to be, and there are all sorts of conjectures.

这里的X到底是谁，就我所知，并没有定论,这个置身于外的观察者的身份仍然不明，关于这点又充满了各种各样的推测。

耶鲁公开课 - 弥尔顿课程节选