3 sentences

1. 士兵们坚守在漫长的阵线上。

   shì​bīng men jiān​shǒu zài màn​cháng de zhèn​xiàn shàng.

   The soldiers held their positions along the long front line.

   Source: Dong Chinese Dictionary

2. 他们建立了广泛的革命统一阵线。

   tā​men jiàn​lì le guǎng​fàn de gé​mìng tǒng​yī zhèn​xiàn.

   They established a broad revolutionary united front.

   Source: Dong Chinese Dictionary

3. 在重大原则问题上，我们必须划清阵线。

   zài zhòng​dà yuán​zé wèn​tí shàng, wǒ​men bì​xū huà​qīng zhèn​xiàn.

   On major issues of principle, we must draw clear battle lines.

   Source: Dong Chinese Dictionary