3 sentences

1. 他故意在网上散布谣言来抹黑对手。

   tā gù​yì zài wǎng​shàng sàn​bù yáo​yán lái mǒ​hēi duì​shǒu.

   He deliberately spread rumors online to smear his opponent.

   Source: Dong Chinese Dictionary

2. 特种兵在执行夜间任务前把脸抹黑。

   tè​zhǒng​bīng zài zhí​xíng yè​jiān rèn​wu qián bǎ liǎn mǒ​hēi.

   Special forces soldiers blacken their faces before performing night missions.

   Source: Dong Chinese Dictionary

3. 公文中的敏感信息被用墨水抹黑了。

   gōng​wén zhōng de mǐn​gǎn xìn​xī bèi yòng mò​shuǐ mǒ​hēi le.

   Sensitive information in the official document was blacked out with ink.

   Source: Dong Chinese Dictionary