___the age of fifteen,she had written scores of articles for a magazine A.At B.Before C.Since D.By
问题描述：
___the age of fifteen,she had written scores of articles for a magazine A.At B.Before C.Since D.By
答
Dshe had written 完成时.
所以要用D by the age...到十五的时候.
B 之前,C自从,都不通.