Paper________aboutathousandyearsagobyCaiLun.A.wasinventedB.isinventedC.inventedD.hasinvented

问题：Paper________aboutathousandyearsagobyCaiLun.A.wasinventedB.isinventedC.inventedD.hasinvented

答案：↓↓↓

蔡晓的回答：

网友采纳　　答案A　　“木轮”与“发明”是被动关系,由athousandyearsago可判断出其为过去式wasinveted.