3 sentences

1. 士兵们在操场上练习听口令。

   shì​bīng men zài cāo​chǎng shàng liàn​xí tīng kǒu​lìng.

   The soldiers are practicing following commands on the drill field.

   Source: Dong Chinese Dictionary

2. 听到教官的口令后，操场上的士兵们迅速由立正转为稍息。

   tīng​dào jiào​guān de kǒu​lìng hòu, cāo​chǎng shàng de shì​bīng men xùn​sù yóu lì​zhèng zhuǎn​wéi shào​xī.

   Upon hearing the drill instructor's command, the soldiers on the field quickly shifted from attention to at ease.

   Source: Dong Chinese Dictionary

3. 只有知道口令的人才能进入营地。

   zhǐ​yǒu zhī​dào kǒu​lìng de rén cái néng jìn​rù yíng​dì.

   Only those who know the password can enter the camp.

   Source: Dong Chinese Dictionary