vein eyelet

例句：

1. 1. The doctor examined the patient's veins to determine the cause of his pain.
   医生检查了病人的静脉来确定他疼痛的原因。
2. 2. Blood flows through the veins in our bodies.
   血液在我们的身体中通过静脉流动。
3. 3. Veins are responsible for carrying oxygenated blood back to the heart.
   静脉负责将氧气饱和的血液送回心脏。