The man's identity remains unknown.

这名男子的身份还是个谜。

《牛津词典》

I am, in part, an ant biologist, so my thoughts turned to what we know about insect life and I knew that much in the world of insects remains unknown.

从某种程度上来说，我是一名蚂蚁生物学家，所以我开始思考我们对昆虫的生命有什么了解，并且我知道昆虫世界对于人类而言仍有许多未知的领域。

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Though the precise harm to our bodies remains unknown, concerns include the microplastics themselves, as well as the fact that they absorb a range of harmful bacteria.

虽然微塑料具体会对我们身体造成怎样的伤害尚不明确，但微塑料本身和他们吸收了大量的有害细菌这一事实让我们忧心忡忡。

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The cause remains unknown.

VOA: special.2009.09.15

But Eric Halgren points out that despite our growing knowledge, much about the human brain remains unknown.

VOA: standard.2010.01.15

He says another three African nationals are still missing and their status remains unknown.

VOA: standard.2009.09.01

But the net effect of the changing Alaskan Arctic on world climate remains unknown.

CNN: Shrub census shows Alaskan Arctic losing its cool

Although she suffered a head injury and later died, the exact of cause of death remains unknown.

BBC: Leigh-on-Sea case shows 'hidden' elderly domestic abuse

What detail remains unknown after the trailer is who exactly the new hero will be of the game.

FORBES: Rockstar Debuts Grand Theft Auto 5 Trailer