sudo apt-get update出现的问题

[lj860603]

请问大家个问题，为什么我每次update时最后都会出现下面的信息：
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错误 http://ubuntu.cn99.com dapper/main Sources
404 Not Found
错误 http://ubuntu.cn99.com dapper/restricted Sources
404 Not Found
错误 http://ubuntu.cn99.com dapper/universe Sources
404 Not Found
错误 http://ubuntu.cn99.com dapper/multiverse Sources
404 Not Found
下载 5B，耗时 11s (0B/s)
无法下载 file:/var/cache/apt-build/repository/dists/apt-build/main/binary-i386/Packages.gz 无法找到该文件
无法下载 http://ubuntu.cn99.com/ubuntu-cn/dists/ ... Sources.gz 404 Not Found
无法下载 http://ubuntu.cn99.com/ubuntu-cn/dists/ ... Sources.gz 404 Not Found
无法下载 http://ubuntu.cn99.com/ubuntu-cn/dists/ ... Sources.gz 404 Not Found
无法下载 http://ubuntu.cn99.com/ubuntu-cn/dists/ ... Sources.gz 404 Not Found
正在读取软件包列表... 完成
E: 有一些索引文件不能下载，它们可能被忽略了，也可能转而使用了旧的索引文件。
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请问这样是什么问题？该怎么解决？

[suenr]

试试用这个 sources.list

# Automatically generated sources.list
# http://www.ubuntulinux.nl/source-o-matic
#
# If you get errors about missing keys, lookup the key in this file
# and run these commands (replace KEY with the key number)
#
# gpg --keyserver subkeys.pgp.net --recv KEY
# gpg --export --armor KEY | sudo apt-key add -

# Ubuntu supported packages (packages, GPG key: 437D05B5)
deb http://cn.archive.ubuntu.com/ubuntu dapper main restricted
deb http://cn.archive.ubuntu.com/ubuntu dapper-updates main restricted
deb http://security.ubuntu.com/ubuntu dapper-security main restricted

# Ubuntu supported packages (sources, GPG key: 437D05B5)
deb-src http://cn.archive.ubuntu.com/ubuntu dapper main restricted
deb-src http://cn.archive.ubuntu.com/ubuntu dapper-updates main restricted
deb-src http://security.ubuntu.com/ubuntu dapper-security main restricted

# Ubuntu community supported packages (packages, GPG key: 437D05B5)
deb http://cn.archive.ubuntu.com/ubuntu dapper universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu dapper-updates universe multiverse
deb http://security.ubuntu.com/ubuntu dapper-security universe multiverse

# Ubuntu community supported packages (sources, GPG key: 437D05B5)
deb-src http://cn.archive.ubuntu.com/ubuntu dapper universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu dapper-updates universe multiverse
deb-src http://security.ubuntu.com/ubuntu dapper-security universe multiverse

[SuperWar3Fan]

你能不能上网？

[lj860603]

谢谢楼上两位朋友，问题已经解决。谢谢。