◎ 题干
—Those scientists invented a robot to care for kids!
—It's not surprising. They ________ wonders all the time.
[     ]
A. worked
B. were working
C. work
D. have been working
◎ 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“—Those scientists invented a robot to care for kids!—It's not surprising. They ________ wonders all the time.[ ]A. workedB. were workingC. workD. have bee…”主要考查了你对  【现在完成进行时】  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。