◎ 题干
According to the companies' websites, the number of active QQ users in China has reached 1 billion, while Qihoo 360 also claims _______ at least 300 million users before June 2010.
[     ]
A. to have  
B. to have had      
C. having    
D. having had
◎ 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“According to the companies' websites, the number of active QQ users in China has reached 1 billion, while Qihoo 360 also claims _______ at least 300 million use…”主要考查了你对  【不定式的完成式】  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。