◎ 题干
Chengdu Metro Line l, _____ into use in October 2010, has made the traffic in this city not so busy.

A. to be put
B. being put
C. having put
D. put
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“Chengdu Metro Line l, _____ into use in October 2010, has made the traffic in this city not so busy. [ ]A. to be put B. being put C. having put D. put …”主要考查了你对  【过去分词】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。