2 sentences for 笔直 (bǐ​zhí — upright)

1. 士兵们在操场上笔直地站着。

   shì​bīng men zài cāo​chǎng shàng bǐ​zhí de zhàn zhe.

   The soldiers stood bolt upright on the drill ground.

   Source: Dong Chinese Dictionary

2. 王宫大门前，两名卫兵笔直地站立着，维持着安全。

   wáng​gōng dà​mén qián, liǎng míng wèi​bīng bǐ​zhí de zhàn​lì zhe, wéi​chí zhe ān​quán.

   Two guards stood straight in front of the palace gate to maintain security.

   Source: Dong Chinese Dictionary