unsolved mystery

基本解释

One of the big unsolved mysteries in evolutionary theory is why creatures are altruistic.
進化論中有一個尚待解決的神秘現象，就是爲什麽生物是利他主義的。
Many unsolved mysteries remain regarding these disasters, perhaps the greatest of which is what caused each of them.
關於這些空前災難還有許多懸而未決之謎，造成大滅絕的原因可能是其中最難的一個。
Some researchers regard sleep as one of the greatest unsolved mysteries of science, even though all animals do it in one form or another.
有些研究者將睡眠認爲是科學中一大未解之謎——雖然每一種動物都會睡覺，以這種或那種的形式。

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