◎ 题干
The Chinese government _____ research into vaccine against H1N1for months, recently many have received the first doses.

A. is doing
B. has done
C. had been doing
D. did
◎ 答案
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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“The Chinese government _____ research into vaccine against H1N1for months, recently many have receivedthe first doses. [ ]A. is doingB. has done C. had been …”主要考查了你对  【过去完成进行时】  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。