2 sentences

1. 这是史无前例的。

   zhè shì shǐ​wú​qián​lì de.

   This is unprecedented.

   Source: OpenSubtitles

2. 这次航天任务取得了史无前例的成功。

   zhè cì háng tiān rèn​wu qǔ​dé le shǐ​wú​qián​lì de chéng​gōng.

   This space mission was an unprecedented success.

   Source: Dong Chinese Dictionary