单选题 The fact ______he does so in so short period of time challenges explanation.
【正确答案】 A
【答案解析】同位语从句。同位语从句常跟在fact，fear，evidence，hope，news等名词的后面，通常用连词that引导，如：There is the news that he is going to study abroad．据说他要去留学了。