2 sentences

1. 他为人刚正不阿，一身正气。

   tā wéi​rén gāng​zhèng​bù'ē, yī shēn zhèng​qì.

   He is upright and unyielding, possessing a strong sense of integrity.

   Source: Dong Chinese Dictionary

2. 医生告诉他，通过增强体内的正气可以提高免疫力。

   yī​shēng gào​su tā, tōng​guò zēng​qiáng tǐ​nèi de zhèng​qì kě​yǐ tí​gāo miǎn​yì​lì.

   The doctor told him that he could improve his immunity by strengthening his body's vital energy.

   Source: Dong Chinese Dictionary