2 sentences

1. 大军正向国境线进军。

   dà​jūn zhèng xiàng guó​jìng​xiàn jìn​jūn.

   The army is marching toward the border.

   Source: Dong Chinese Dictionary

2. 边防战士们冒着严寒，小心地跨过了那条国境线。

   biān​fáng zhàn​shì men mào zhe yán​hán, xiǎo​xīn de kuà​guò le nà tiáo guó​jìng​xiàn.

   The border guards braved the severe cold and carefully crossed the border line.

   Source: Dong Chinese Dictionary