extra arm外臂, 可变臂extraadj.额外的n.额外之物；临时演员adv.特别地Extracorporeal Grculation体外循环extraterritorial material域外题材extracurricular athletics课外体育活动Extra- fitness activity课外健身extracellular polypeptide胞外多肽extra-atmospheric abort大气层外中断飞行Extraperitoneal colostomy肠造口术extra precision machining超精加工extra-heavy crown glass特重冕玻璃Extraeorpoeal circulation体外循环