gas fluid

例句：

1. 1. The gas flowedthrough the pipe at a steady rate.
   气体以稳定的速率流过管道。
2. 2. Gasesare composed of molecules that can be brokendown into simpler substances.
   气体是由可以分解成更简单物质的分子组成的。
3. 3.The liquid is clear and has a pleasantsmell.
   这种液体清澈，闻起来很香。