protected void grvw_timu_RowDataBound(object sender, GridViewRowEventArgs e)//显示符合条件的题目的GridView,显示行号
 {
     if (e.Row.RowIndex != -1)
     {
         e.Row.Cells[0].Text = (e.Row.RowIndex + 1).ToString();//显示行号
         string zuoyeid = Request.QueryString["zuoyeid"];
         //设置添加和删除按钮的可用状态
         int rowindex = e.Row.RowIndex;
         //然后根据行号,来得到主键
         string questionid = grvw_timu.DataKeys[rowindex].Value.ToString();
         Button tianjiabtn = (Button)(e.Row.FindControl("btn_add")); //添加按钮
         Button shanchubtn = (Button)(e.Row.FindControl("btn_del")); //删除按钮
         if (ZuoyeInfo.IsTimuInZuoye(zuoyeid, questionid))
         {
             tianjiabtn.Enabled = false;
             shanchubtn.Enabled = true;
         }
         else
         {
             tianjiabtn.Enabled = true;
             shanchubtn.Enabled = false;
         }
     }
 }