問題詳情：
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
【回答】
B
知識點：非謂語動詞
題型：選擇題
