◎ 题干
It is believed that a new kind of drug ______ by the scientists and they are hopeful that they
will succeed in a couple of months.     
[     ]
A. has been developed  
B. is being developed  
C. is developing  
D. has developed
◎ 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“It is believed that a new kind of drug ______ by the scientists and they are hopeful that they will succeed in a couple of months. [ ]A. has been developedB. …”主要考查了你对  【现在进行时的被动语态】  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。