1 sentence

1. 那个失踪案件的真相仍然是一个深藏的谜团。

   nà gè shī​zōng àn​jiàn de zhēn​xiàng réng​rán shì yī gè shēn cáng de mí​tuán.

   The truth behind that disappearance case remains a deep mystery.

   Source: Dong Chinese Dictionary