mid vein

例句：

1. 1. The doctor found a mid vein in the patient's arm.
   医生在病人的手臂里发现了一条中脉。
2. 2.The scientist used a microscope to observe the mid vein of the plant.
   科学家用显微镜观察了植物的中脉。
3. 3.The artist painted the mid vein of the butterfly with vibrant colors.
   艺术家用鲜艳的颜色描绘了蝴蝶的中脉。