在GridView1_RowCommand事件中,如何取Rowindex

<EditItemTemplate>
                        <asp:CheckBoxList ID="cblXueke" runat="server" DataTextField="Id"
                            DataValueField="FullName" RepeatDirection="Horizontal" RepeatLayout="Flow">
                        </asp:CheckBoxList>
                        <asp:LinkButton ID="lkDel" runat="server" CommandName="DelXueke" CommandArgument='<%# ((GridViewRow) Container).RowIndex %>'>删除选中科目</asp:LinkButton>
                    </EditItemTemplate>