3 sentences

1. 这份文件被列为绝密。

   zhè fèn wén​jiàn bèi liè​wéi jué​mì.

   This document is classified as top secret.

   Source: Dong Chinese Dictionary

2. 联邦调查局需要你参与一项绝密任务。

   lián​bāng diào​chá​jú xū​yào nǐ cān​yù yī xiàng jué​mì rèn​wu.

   The FBI needs you to take part in a top-secret mission.

   Source: OpenSubtitles

3. 政府决定在五十年后将这些绝密档案解密。

   zhèng​fǔ jué​dìng zài wǔ​shí nián hòu jiāng zhè​xiē jué​mì dàng'àn jiě​mì.

   The government decided to declassify these top-secret files after fifty years.

   Source: Dong Chinese Dictionary