词根词缀：extra-, extro-, extr-, exter-

【来源及含义】Latin: beyond, outside, on the outside, outward, external

【同源单词】Ab extra, ad extra, ad extremum, exteriorly, external, external reforming

词根词缀：tra-, tract-, trac-, -tractive, -traction, -tracting, treat-, trai-

【来源及含义】Latin: drag, draw together; a drawing out or pulling

【同源单词】abstract, abstract, abstracted, abstractedly, abstractedness, abstraction