2 sentences

1. 请大家保持肃静。

   qǐng dà​jiā bǎo​chí sù​jìng.

   Please remain quiet.

   Source: Dong Chinese Dictionary

2. 从没见过这么多人如此肃静。

   cóng méi jiàn guo zhè​me duō rén rú​cǐ sù​jìng.

   I've never seen so many people so quiet.

   Source: OpenSubtitles