Hayley教口语，“成了一个谜”用英语怎么说？

Shroud /ʃraʊd/ 作动词表示“覆盖，遮盖”

to be a matter about which very little is known or understood

成了一个谜，笼罩在谜团中

Her whereabouts have been shrouded in secrecy since she received the death threat.

自从收到死亡威胁后，她的行踪就成了一个谜。

The process was shrouded in secrecy and little explanation was given as to her qualifications for the post.

整个过程是秘密进行的，而且对于她出任该职务的资格，也没有多少解释。