在GridView里面添加CheckBox，如何实现哪一行被选中

一：添加CheckBox
<asp:GridView>
     <Columns>
          <asp:TemplateField HeaderText="选择">
          <ItemStyle HorizontalAlign="Center" Height="35px" Width="720px"/>
          <ItemTemplate>
          <asp:CheckBox  ID="CheckBox" runat="server" ></asp:CheckBox>   
          </ItemTemplate>   
          </asp:TemplateField>
          <asp:BoundField DataField="Code" HeaderText="学号" SortExpression="Code">
              <ItemStyle HorizontalAlign="Center" Height="35px" Width="720px"/>
          </asp:BoundField>
          <asp:BoundField DataField="Name" HeaderText="姓名">
              <ItemStyle HorizontalAlign="Center" Height="35px" Width="720px"/>
          </asp:BoundField>
          <asp:BoundField DataField="SchoolName" HeaderText="所在学校">
              <ItemStyle HorizontalAlign="Center" Height="35px" Width="720px"/>
          </asp:BoundField>
          <asp:BoundField DataField="Email" HeaderText="E-mail">
              <ItemStyle HorizontalAlign="Center" Height="35px" Width="720px"/>
          </asp:BoundField>
     </Columns>
 </asp:GridView>
二：查看哪一行的CheckBox被选中
foreach(GridViewRow row in this.StudentGridView.Rows)
        {
            Control ctrl = row.FindControl("CheckBox");
         
                if ((ctrl as CheckBox).Checked)
                {
                    TableCellCollection cell = row.Cells;
                    string studentCode = cell[1].Text;
                 }
                
         }