在伪静态规则下，怎么修改网站默认首页

linux主机，原来默认首页是Index.php，我想改成cx.php之类的。我的空间商那里不支持直接修改默认首页。
我在,htaccess里加了DirectoryIndex cx.php index.html index.php,的确改过来了。但是伪静态挂掉了。原来伪静态是好的，但是把这句加到第一句，一开伪静态，网站直接无法访问，加在最后，不起作用。。求解在伪静态环境下，怎么添加DirectoryIndex cx.php。我的是多多返利程序。而且是安装在子目录下的。
# 将 RewriteEngine 模式打开
RewriteEngine On
RewriteBase /# Rewrite 定义各重写规则
RewriteRule mall/list-(.*)-(\d+)\.html$ /index.php\?mod=mall&act=list&cid=$1&page=$2
RewriteRule mall/list-(.*)\.html$ /index.php\?mod=mall&act=list&cid=$1
RewriteRule mall/list\.html$ /index.php\?mod=mall&act=list
RewriteRule mall/view-(\d+)-(.*)-(\d+)\.html$ /index.php\?mod=mall&act=view&id=$1&do=$2&page=$3
RewriteRule mall/view-(\d+)-(.*)\.html$ /index.php\?mod=mall&act=view&id=$1&do=$2
RewriteRule mall/view-(\d+)\.html$ /index.php\?mod=mall&act=view&id=$1
RewriteRule mall/goods-(.*)-(\d+)-(\d+)-(\d+)-(\d+)-(.*)-(\d+)\.html$ /index.php\?mod=mall&act=goods&merchantId=$1&order=$2&start_price=$3&end_price=$4&list=$5&q=$6&page=$7
RewriteRule mall/goods-(.*)\.html$ /index.php\?mod=mall&act=goods&q=$1
RewriteRule mall/goods\.html$ /index.php\?mod=mall&act=goods
RewriteRule article/index\.html$ /index.php\?mod=article&act=index
RewriteRule article/$ /index.php\?mod=article&act=index
RewriteRule article$ /index.php\?mod=article&act=index
RewriteRule article/list-(.*)-(\d+)\.html$ /index.php\?mod=article&act=list&cid=$1&page=$2
RewriteRule article/list-(.*)\.html$ /index.php\?mod=article&act=list&cid=$1
RewriteRule article/list\.html$ /index.php\?mod=article&act=list
RewriteRule article/view-(\d+)\.html$ /index.php\?mod=article&act=view&id=$1
RewriteRule huodong/list-(\d+)-(\d+)\.html$ /index.php\?mod=huodong&act=list&cid=$1&page=$2
RewriteRule huodong/list-(\d+)\.html$ /index.php\?mod=huodong&act=list&page=$1
RewriteRule huodong/list\.html$ /index.php\?mod=huodong&act=list
RewriteRule huodong/view-(\d+)\.html$ /index.php\?mod=huodong&act=view&id=$1
RewriteRule huan/list-(\d+)-(\d+)\.html$ /index.php\?mod=huan&act=list&cid=$1&page=$2
RewriteRule huan/list-(\d+)\.html$ /index.php\?mod=huan&act=list&cid=$1
RewriteRule huan/list\.html$ /index.php\?mod=huan&act=list
RewriteRule huan/view-(\d+)\.html$ /index.php\?mod=huan&act=view&id=$1
RewriteRule tao/index\.html$ /index.php\?mod=tao&act=index
RewriteRule tao/$ /index.php\?mod=tao&act=index
RewriteRule tao$ /index.php\?mod=tao&act=index
RewriteRule tao/list-(.*)-(.*)-(\d+)-(\d+)\.html$ /index.php\?mod=tao&act=list&cid=$1&q=$2&list=$3&page=$4
RewriteRule tao/list-(.*)-(\d+)\.html$ /index.php\?mod=tao&act=list&cid=$1&page=$2
RewriteRule tao/list-0-(.*)\.html$ /index.php\?mod=tao&act=list&cid=0&q=$1
RewriteRule tao/list-(.*)\.html$ /index.php\?mod=tao&act=list&cid=$1
RewriteRule tao/list\.html$ /index.php\?mod=tao&act=list
RewriteRule tao/view-(.*)-(.*)-(.*)\.html$ /index.php\?mod=tao&act=view&iid=$1&promotion_price=$2&promotion_endtime=$3
RewriteRule tao/view-(.*)\.html$ /index.php\?mod=tao&act=view&iid=$1
RewriteRule tao/shop-(.*)-(\d+)\.html$ /index.php\?mod=tao&act=shop&nick=$1&list=$2
RewriteRule tao/shop-(.*)\.html$ /index.php\?mod=tao&act=shop&nick=$1
RewriteRule tao/zhe-(.*)-(\d+)-(\d+)\.html$ /index.php\?mod=tao&act=zhe&q=$1&cid=$2&page=$3
RewriteRule tao/zhe-(.*)\.html$ /index.php\?mod=tao&act=zhe&q=$1
RewriteRule tao/zhe\.html$ /index.php\?mod=tao&act=zhe
RewriteRule tao/coupon-(.*)\.html$ /index.php\?mod=tao&act=coupon&q=$1
RewriteRule tao/coupon\.html$ /index.php\?mod=tao&act=coupon
RewriteRule tao/juhuasuan\.html$ /index.php\?mod=tao&act=juhuasuan
RewriteRule tao/cha\.html$ /index.php\?mod=tao&act=cha
RewriteRule tao/jiu\.html$ /index.php\?mod=tao&act=jiu
RewriteRule shop/list-(\d+)-(\d+)-(\d+)-(\d+)-(.*)-(\d+)-(\d+)\.html$ /index.php\?mod=shop&act=list&cid=$1&start_level=$2&end_level=$3&type=$4&nick=$5&px=$6&page=$7
RewriteRule shop/list-(.*)-(\d+)\.html$ /index.php\?mod=shop&act=list&cid=$1&page=$2
RewriteRule shop/list-(.*)\.html$ /index.php\?mod=shop&act=list&cid=$1
RewriteRule shop/list\.html$ /index.php\?mod=shop&act=list
RewriteRule baobei/list-(.*)-(\d+)-(.*)-(\d+)\.html$ /index.php\?mod=baobei&act=list&sort=$1&cid=$2&q=$3&page=$4
RewriteRule baobei/list-(\d+)-(\d+)\.html$ /index.php\?mod=baobei&act=list&cid=$1&page=$2
RewriteRule baobei/list-(\d+)\.html$ /index.php\?mod=baobei&act=list&cid=$1
RewriteRule baobei/list\.html$ /index.php\?mod=baobei&act=list
RewriteRule baobei/user-(\d+)-(\d+)-(\d+)\.html$ /index.php\?mod=baobei&act=user&uid=$1&xs=$2&page=$3
RewriteRule baobei/user-(\d+)-(\d+)\.html$ /index.php\?mod=baobei&act=user&uid=$1&xs=$2
RewriteRule baobei/user-(\d+)\.html$ /index.php\?mod=baobei&act=user&uid=$1
RewriteRule baobei/view-(\d+)\.html$ /index.php\?mod=baobei&act=view&id=$1
RewriteRule tuan/list-(\d+)-(\d+)-(\d+)-(.*)-(\d+)\.html$ /index.php\?mod=tuan&act=list&cid=$1&mall_id=$2&city_id=$3&sort=$4&page=$5
RewriteRule tuan/list-(\d+)-(\d+)-(.*)\.html$ /index.php\?mod=tuan&act=list&cid=$1&city_id=$2&sort=$3
RewriteRule tuan/list-(\d+)-(\d+)\.html$ /index.php\?mod=tuan&act=list&cid=$1&page=$2
RewriteRule tuan/list-(.*)-(\d+)\.html$ /index.php\?mod=tuan&act=list&q=$1&page=$2
RewriteRule tuan/list-(\d+)\.html$ /index.php\?mod=tuan&act=list&cid=$1
RewriteRule tuan/list-(.*)\.html$ /index.php\?mod=tuan&act=list&q=$1
RewriteRule tuan/list\.html$ /index.php\?mod=tuan&act=list
RewriteRule tuan/view-(\d+)\.html$ /index.php\?mod=tuan&act=view&id=$1
RewriteRule help/index-(\d+)\.html$ /index.php\?mod=help&act=index&cid=$1
RewriteRule help/index\.html$ /index.php\?mod=help&act=index
RewriteRule help/$ /index.php\?mod=help&act=index
RewriteRule help$ /index.php\?mod=help&act=index
RewriteRule about/index-(\d+)\.html$ /index.php\?mod=about&act=index&id=$1
RewriteRule about/index\.html$ /index.php\?mod=about&act=index
RewriteRule about/$ /index.php\?mod=about&act=index
RewriteRule about$ /index.php\?mod=about&act=index
RewriteRule sitemap/index\.html$ /index.php\?mod=sitemap&act=index
RewriteRule sitemap/$ /index.php\?mod=sitemap&act=index
RewriteRule sitemap$ /index.php\?mod=sitemap&act=index
RewriteRule paipai/index\.html$ /index.php\?mod=paipai&act=index
RewriteRule paipai/$ /index.php\?mod=paipai&act=index
RewriteRule paipai$ /index.php\?mod=paipai&act=index
RewriteRule paipai/list-(\d+)-(.*)-(\d+)-(.*)-(\d+)-(\d+)-(\d+)-(\d+)\.html$ /index.php\?mod=paipai&act=list&cid=$1&q=$2&sort=$3&property=$4&begPrice=$5&endPrice=$6&list=$7&page=$8
RewriteRule paipai/list-(.*)\.html$ /index.php\?mod=paipai&act=list&q=$1
RewriteRule paipai/list\.html$ /index.php\?mod=paipai&act=list
RewriteRule tbimg/(.*)\.jpg$ /comm/showpic.php\?pic=$1
RewriteRule index\.html$ /index.php