His essay, ____many times,was brief and to the point,and therefore won the first prize in the writing petition.A.polishing upB.having polished upC.to be polished upD.having been polished up
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D解析 having been polished up为现在分词完成式的被动式，作定语修饰essay。根据后面的内容可知，他的文章已获得了一等奖，而polish up (修改，润饰)应是在此之前，故用其完成式。句意为：他的文章，经多次修改后，简洁而又切题，因此在作文比赛中赢得了一等奖。