extra old特等陈年威士忌酒extraadj.额外的n.额外之物；临时演员adv.特别地extra-European system欧外系统extragalactic astronomy河外天文学extracurriliar training课余体育训练extracoronal attachment牙冠外固位体extrahepatic bile ducts肝外胆管extra-thick coal seam特厚煤层extraterrestrial planet地外行星extra-anatomic bypass解剖外旁路Extra-cellular Matrix细胞外基质extra marital sexuality婚外性行为