2 sentences

1. 鸡在上下颠倒的时候不能吞咽。

   jī zài shàng​xià diān​dǎo de shí​hou bù​néng tūn​yàn.

   Chickens can't swallow while they are upside down.

   Source: CCMatrix

2. 一只小鸟把头上下快速摆动着。

   yī zhī xiǎo​niǎo bǎ tóu shàng​xià kuài​sù bǎi​dòng zhe.

   A little bird was bobbing its head up and down.

   Source: UM-Corpus: Spoken