________one of themost important inventions of the time, the computer helps people living indifferent countries to do a lot of things.
A.Knowing tobeB.It wasknownC.Known asD.As wasknown to be在线课程C
解析：
computer与know之间是动宾关系，状语用过去分词，表被动。译文：计算机被认为是这个时代最重要的发明，它帮助居住在不同国家的人们做了很多事情。