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;
}

}