circulating circle

例句：

1. 1. The heart is the primarycirculatory system in our body.
   心脏是我们身体的主要循环系统。
2. 2. The doctoradvised him to maintain a healthy circulatory system.
   医生建议他保持一个健康的循环系统。
3. 3. The scientist discovered a newmethod to improve the efficiency of thecirculatory system.
   科学家发现了一种新的方法来提高循环系统的效率。