3 sentences

1. 无辜的人们命悬一线。

   wú​gū de rén​men mìng xuán yī​xiàn.

   Innocent lives are at stake.

   Source: OpenSubtitles

2. 医护人员奋战在一线。

   yī​hù rén​yuán fèn​zhàn zài yī​xiàn.

   Medical staff are fighting on the front lines.

   Source: Dong Chinese Dictionary

3. 医生们正竭尽全力，为他争取一线生机。

   yī​shēng men zhèng jié​jìn​quán​lì, wèi tā zhēng​qǔ yī​xiàn shēng​jī.

   Doctors are doing their utmost to fight for a slim chance of survival for him.

   Source: Dong Chinese Dictionary