请教大全No.41---这道题好难！

howardwang

of those born since 1955, six percent had become depressed by age twenty-four

前如果是分号，才有可能正确，不过，看上去好像是逗号。

这里用完成时很恰当阿，看来楼主的复习复习时态了，因为一半句讲不清楚。

A中的they指代Americans。