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

I could take an unknown gas and put it in and measure it and then say, wow, those are the lines that are characteristic of sodium.

我取一种未知气体，把它放到管里,然后检测它，哇，这些线是钠的特征。

麻省理工公开课 - 固态化学导论课程节选

The mathematical theory of probability was unknown until that time and you can see that insurance suddenly made an appearance at that time.

在那之前,概率的数学理论,是不存在的,而随着概率论的出现,保险业也突然出现了

耶鲁公开课 - 金融市场课程节选

Afghan and NATO officials say that Taliban insurgents in the northern Kunduz province were driving two hijacked fuel trucks to an unknown destination when fighter planes located them on a river bank and bombed them.

VOA: standard.2009.09.04