◎ 题干
_____ on the subject for half an hour, Liu Ying suddenly stopped.
[     ]
A. To be worked
B. To work
C. Having worked
D. Having been worked
◎ 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“_____ on the subject for half an hour, Liu Ying suddenly stopped. [ ]A. To be worked B. To work C. Having worked D. Having been worked …”主要考查了你对  【现在分词的完成式】  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。