2 sentences

1. 空气是流体，不是液体。

   kōng​qì shì liú​tǐ, bù​shì yè​tǐ.

   Air is a fluid but not a liquid.

   Source: UM-Corpus: Science

2. 沙子既是固体又是流体。

   shā​zi jì shì gù​tǐ yòu shì liú​tǐ.

   Sand is both a solid and a fluid.

   Source: CCMatrix