huyền bí 
mystery like: Rätsel → →
das Rätsel ☊ 
ô chữ ☊ 
☊ das Kreuzworträtsel ☊ ô chữ ☊ ☊ Rätsel ☊ 谜语 ☊ míyǔ Kreuzworträtsel ☊ 填字游戏 ☊ tiánzì yóuxì to clear up a mystery/difficulty/misunderstanding ☊ clear sth up ☊
It is one of the great unsolved mysteries of this century. ☊ mystery ☊
Their motives remain a mystery. ☊ mystery ☊
It's a complete mystery to me why they chose him. ☊ mystery ☊
He's a bit of a mystery. ☊ mystery ☊
to solve an equation/a puzzle/a riddle ☊ solve ☊
What happened to them remains somewhat of a mystery. ☊ somewhat ☊