我的程序是这样的：
result:=tMsAddItem(popuphandle, 1, 0, "复习")
result:=tMsAddItem(popuphandle, 2, 0, "-")
result:=tMsAddItem(popuphandle, 3, 0, "新授")
result:=tMsAddItem(popuphandle, 3, 1, "第一部分")
result:=tMsAddItem(popuphandle, 3, 2, "第二部分")
result:=tMsAddItem(popuphandle, 3, 3, "第三部分")
result:=tMsAddItem(popuphandle, 4, 0, "练习")
result:=tMsAddItem(popuphandle, 5, 0, "思考题")
result:=tMsAddItem(popuphandle, 6, 0, "-")
result:=tMsAddItem(popuphandle, 7, 0, "退出")
如果在“第一部分”下面再做第三级菜单怎么做呢？