更新我的包列表时收到这些错误消息。也许你可以帮助我：
sudo apt-get update
Hit http://repo.steampowered.com precise InRelease
Ign http://us.archive.ubuntu.com trusty InRelease
Hit http://repo.steampowered.com precise/steam Sources
Ign http://us.archive.ubuntu.com trusty-security InRelease
Hit http://repo.steampowered.com precise/steam amd64 Packages
Hit http://repo.steampowered.com precise/steam i386 Packages
Ign http://us.archive.ubuntu.com trusty-updates InRelease
Hit http://us.archive.ubuntu.com trusty Release.gpg
Get:1 http://us.archive.ubuntu.com trusty-security Release.gpg [933 B]
Get:2 http://us.archive.ubuntu.com trusty-updates Release.gpg [933 B]
Hit http://us.archive.ubuntu.com trusty Release
Get:3 http://us.archive.ubuntu.com trusty-security Release [58.5 kB]
Get:4 http://us.archive.ubuntu.com trusty-updates Release [58.5 kB]
Hit http://us.archive.ubuntu.com trusty/main Sources
Hit http://us.archive.ubuntu.com trusty/restricted Sources
Hit http://us.archive.ubuntu.com trusty/universe Sources
Hit http://us.archive.ubuntu.com …apt ×1