2 sentences for 烏 (wū)

1. 他的脸色发乌，看起来像是生病了。

   tā de liǎn​sè fā wū, kàn​qǐ​lai xiàng​shì shēng​bìng le.

   His face turned dark; he looks like he's sick.

   Source: Dong Chinese Dictionary

2. 老师说，“乌”字指黑色的鸟，比“鸟”字少一点。

   lǎo​shī shuō,“ wū” zì zhǐ hēi​sè de niǎo, bǐ“ niǎo” zì shǎo yī​diǎn.

   The teacher said that the character 'wu' (乌) refers to a black bird and is written with one less dot than the character 'niao' (鸟).

   Source: Dong Chinese Dictionary