题目内容
【题目】Silk_________ one of the primary goods traded along the Silk Road by about 100 BC.
A. had become B. wasbecoming
C.has become D. isbecoming
【答案】A
【解析】试题分析:句意:到公元前100年为止,丝绸已经成为丝绸之路上交易的主要商品之一。时间状语是by+过去时间,谓语用过去完成时。故选A。
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