[解析]
49.A.细节理解题.根据第二段的She was cleaning out the attic(阁楼)one day when she came across an old dusty manuscript(手稿).On its top page were the words,"By O.Henry"可知那位小女孩的母亲一天打扫阁楼上发现布满尘土的旧手稿,手稿上写着O.Henry的签名,故选A.
50.B.细节理解题.根据第二段的My father had never read the story before,but it sounded like O.Henry,and he knew that O.Henry had once lived in Houston可知我父亲从没有听说过这个故事,但是他知道O.Henry曾住在Houston,故选B.
51.C.猜测词义题.根据前文作者的父亲找到一位专家应是"证明"是O.Henry的作品.A命名;B对待;C证明;D描述.故选C.
52.A.细节理解题.根据最后一段的"My father then set out to sell it"可知,我父亲然后出发去把它卖掉,可知选A.