In this technological eraonce took a century now only takes a month.A. whichB. thatC. when

发布时间：2020-08-16 21:05:59

In this technological era     once took a century now only takes a month.
A. which
B. that
C. when
D. What

网友回答

A. which
B. that
C. when
(答案→)D. What
解析：考查名词性从句。What once took a century now 做takes的主语，是主语从句。从句中缺少took的主语，故选What。
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