The Chinese mainland has 157 billionaires as of 2013， second in the number of billionaires worldwide．
A. having ranked
B. ranked
C. to rank
D. ranking
网友回答
A. having ranked
B. ranked
C. to rank
(答案→)D. ranking
解析：句意：2013年中国大陆有157个亿万富翁，在全世界的亿万富翁的数量上排名第二。The Chinese mainland和rank是主动关系，这里是现在分词做伴随状语，选D。