________ the poem a second time, the meaning will become clearer to you．
A.Your having readB.While readingC.If readingD.When you read在线课程D
解析：
选项A是动名词，与后面的成分存在语法错误；
选项B、C的逻辑主语应该是人，但此句的逻辑主语是the meaning。D项为最佳答案。