<iewc:treeview id="TreeView1" runat="server" BackColor="Transparent" ShowToolTip="False" AutoSelect="True"
SelectExpands="True" HoverStyle="color:black;text-decoration:underline;" SystemImagesPath="/AE/images/webctrl_client/1_0/treeimages/"
ExpandLevel="3">
ExpandLevel="3"就是需要展开的层次