3 sentences

1. 我们要保持一定的安全距离。

   wǒ​men yào bǎo​chí yī​dìng de ān​quán jù​lí.

   We need to maintain a certain safety distance.

   Source: Dong Chinese Dictionary

2. 保持安全距离。

   bǎo​chí ān​quán jù​lí.

   Keep a safe distance.

   Source: OpenSubtitles

3. 天雨路滑，行车时请保持安全距离。

   tiān yù lù huá, xíng​chē shí qǐng bǎo​chí ān​quán jù​lí.

   The road is slippery due to rain; please maintain a safe distance while driving.

   Source: Dong Chinese Dictionary