cardiovascular system

例句：

1. 1. The heart is the primary organ ofthe cardiovascular system.
   心脏是心血管系统的主器官。
2. 2. The study of the cardiovascular system iscrucial for understanding human health.
   研究心血管系统对于理解人类健康至关重要。
3. 3. Cardiovascular diseases are amajor cause of death worldwide.
   心血管疾病是全球死亡的主要原因。