如何备份U盘系统？朕不是老袁

系统安装好了，更新了两次，发现不能让系统自动查找快的源服务器，点了“其它站点”没反应，在软件中心中可以显示要安装的软件，点了安装也没反应。

12.04也是这样。

那个查找最快的服务器可能找到的不是最快的，建议手工在几个服务器下载测试一下。
软件中心用不了就用新立得吧

刚刚发现更新也不行了，上网正常，源列表是
deb http://mirrors.163.com/ubuntu/ oneiric main universe restricted multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric main universe restricted multiverse
deb http://mirrors.163.com/ubuntu/ oneiric-security universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ oneiric-security universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ oneiric-updates universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ oneiric-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ oneiric-proposed universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ oneiric-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ oneiric-backports universe main multiverse restricted
deb http://archive.ubuntu.com/ubuntu precise main universe multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ oneiric-updates universe main multiverse restricted

我是新手，本来准备用软件中心来安装新立得的，但还没来得及，呵呵。