These observations, along with the likely existence of neutralinos, mean that dark matter looks like a known unknown.

这些观测，包括neutralinos存在的可能性，意味着暗物质看上去像是一个已知的未知，我们知道它的存在，但是却知之甚少。

youdao

The LHC should, though, if all goes according to plan, show up one very well known unknown by creating tiny black holes.

如果一切进展顺利，LHC应制造出一些微型黑洞，以验证这个著名的已知之未知。

youdao

A known unknown is when you realize a specific intangible exists but can't quantify how much, such as traffic (if you live in Los Angeles you know exactly what I'm talking about).

“已知的未知”是指你意识到一些无形限制的存在，但你无法进行具体量化，例如交通(如果你住在洛杉矶，你肯定知道我在说什么)。

youdao

Diakite,who is also known as Toumba, escaped the attack and is still at large with an unknown number of soldiers from the presidential guard.

VOA: standard.2009.12.07

That's how by either balancing the unknown force with a known force or by simply measuring the acceleration as I fall towards this podium and multiplying by mass, you can find the force that exerts on me.

我们既可以让未知力与已知力平衡,也可以只测量我冲向讲台时加速度的大小,再与我的质量相乘,都能求出作用在我身上的力的大小

耶鲁公开课 - 基础物理课程节选

However nasty influenza is, though (and it can be very nasty indeed), it is what Donald Rumsfeld would call a known unknown.

ECONOMIST: Bird flu and public health

If Spain tips into crisis in the next few months, the odds are that it will be because of something nasty happening to balance sheets at the local level which shocks the markets - in Donald Rumsfeld's phrase, that is the 'known unknown' that makes everyone nervous.

BBC: Eurozone crisis: what have we learned?

Spread the marketing funds wide to introduce the public to lesser-known or unknown writers and new writing.

FORBES: The 21st Century Novel: Jaded Ibis Sees a 'Mashup'