extra arm外臂, 可变臂
extraadj.额外的n.额外之物;临时演员adv.特别地
Extracorpereal circulation体外循环
extrapleural pneumonolysis胸膜外肺松解术
extra-budgetary spending超支挪用
extra-curricular reading课外阅读
extrafolia-ceous stipule叶外托叶
extraarticular arthrodesis关节外关节固定术
extra - coronal retainer冠外固位体
extra- budgetary revenue预算外资金
extra statutory concession法外宽免
extra-ordinary recources[经] 特别救济手段
"Vesuvius erupts once in a while"