By the end of 2007, about half a million people had flooded into the city, ________ up around 10 percent of its total population．

A.make

B.made

C.making

D.to be made

答案及解析： C

解析：

考查非谓语动词作状语。前文提到大量人口流入城市，而正是这些流入城市的人口占了城市总人口的10％，现在分词making用作结果状语。本题难。