self-circulation

例句：

1. 1. The self-circulation of the blood in the body is essential for maintaining health.
   身体内血液的自我循环对于保持健康至关重要。
2. 2. In a closed system, self-circulation ensures that all components are properly balanced.
   在一个封闭系统中，自我循环确保所有组件都得到适当的平衡。
3. 3.The self-circulation of the river helps to distribute nutrients and oxygen throughout the ecosystem.
   河流的自循环有助于在整个生态系统中分配营养物质和氧气。