function show_menu(now_num) { 	
 var max_num = 3;
 var link_url = "basic-tree-";
 var css_1 = "on";
 var css_2 = "off";
 for (var i=1; i<max_num;i++) {
	if(i == now_num) {
		document.write("&nbsp;&nbsp;&nbsp;<a href='"+link_url+ i +".htm' id ="+css_1+">"+i+"</a>" );
	}else{
		document.write("&nbsp;&nbsp;&nbsp;<a href='"+link_url+ i +".htm' id ="+css_2+">"+i+"</a>" );
		}
	} 
}