unsolved mystery

基本解释

One of the big unsolved mysteries in evolutionary theory is why creatures are altruistic.
进化论中有一个尚待解决的神秘现象，就是为什么生物是利他主义的。
Many unsolved mysteries remain regarding these disasters, perhaps the greatest of which is what caused each of them.
关于这些空前灾难还有许多悬而未决之谜，造成大灭绝的原因可能是其中最难的一个。
Some researchers regard sleep as one of the greatest unsolved mysteries of science, even though all animals do it in one form or another.
有些研究者将睡眠认为是科学中一大未解之谜——虽然每一种动物都会睡觉，以这种或那种的形式。

Finally,there's a section that talks more about the unsolved mysteries and particularly the role that the Large Hadron Collider would play in that."

These geometric forms present one of the biggest unsolved mysteries in pre-historic exploration.
FORBES: Human Ingenuity: A 100,000-Year-Old Story
If you like your mysteries unsolved, you can even take the Finnish tour.
FORBES: Guilty Landscapes: Oxford, Ystad, Amsterdam and Sodermalm