one-way flow

• 单向流动

one-way flow的用法和样例：

例句

1. But birds breathe in one direction, like a jet engine, with the cells of the lungs absorbing oxygen from the air as it passes by.
   但是鸟类的气流是单向流动的，像一个飞机引擎，吸气时空气经微气管从体外进入气囊，呼气时气体经微气管从气囊排出体外。