当我使用时sudo apt-get update，我得到以下输出，因此我无法安装 git send-email 包。
Err http://dl.google.com stable/main Translation-en_IN
Connection failed [IP: 216.58.220.46 80]
Err http://ppa.launchpad.net trusty/main i386 Packages
Connection failed
Err http://archive.canonical.com precise/partner Sources
Connection failed [IP: 91.189.92.191 80]
Err http://dl.google.com stable/main Translation-en
Connection failed [IP: 216.58.220.46 80]
Err http://extras.ubuntu.com precise/main Sources
Connection failed [IP: 91.189.92.152 80]
Err http://archive.canonical.com precise/partner amd64 Packages
Connection failed [IP: 91.189.92.191 80]
Err http://dl.google.com stable/main amd64 Packages
Connection failed [IP: 216.58.220.46 80]
Err http://extras.ubuntu.com precise/main amd64 Packages
Connection failed [IP: 91.189.92.152 80]
Err http://archive.canonical.com precise/partner i386 Packages
Connection failed [IP: 91.189.92.191 80]
Err http://dl.google.com stable/main i386 Packages
Connection failed [IP: 216.58.220.46 80]
Err http://extras.ubuntu.com precise/main i386 Packages
Connection failed [IP: 91.189.92.152 80]
Err http://archive.canonical.com precise/partner Translation-en_IN
Connection failed [IP: 91.189.92.191 80]
Err http://extras.ubuntu.com precise/main Translation-en_IN
Connection failed [IP: 91.189.92.152 80]
Err http://archive.canonical.com precise/partner Translation-en
Connection failed [IP: 91.189.92.191 80]
Err http://extras.ubuntu.com precise/main Translation-en
Connection failed [IP: 91.189.92.152 80]
Err http://us.archive.ubuntu.com precise/main Sources
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise/restricted Sources
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise/universe Sources
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise/multiverse Sources
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise/main amd64 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise/restricted amd64 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise/universe amd64 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise/multiverse amd64 Packages
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise/main i386 Packages
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise/restricted i386 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise/universe i386 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise/multiverse i386 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise/main Translation-en_IN
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise/main Translation-en
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise/multiverse Translation-en_IN
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise/multiverse Translation-en
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise/restricted Translation-en_IN
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise/restricted Translation-en
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise/universe Translation-en_IN
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise/universe Translation-en
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-security/main Sources
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-security/restricted Sources
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-security/universe Sources
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-security/multiverse Sources
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-security/main amd64 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-security/restricted amd64 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-security/universe amd64 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-security/multiverse amd64 Packages
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-security/main i386 Packages
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-security/restricted i386 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-security/universe i386 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-security/multiverse i386 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-security/main Translation-en_IN
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-security/main Translation-en
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-security/multiverse Translation-en_IN
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-security/multiverse Translation-en
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-security/restricted Translation-en_IN
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-security/restricted Translation-en
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-security/universe Translation-en_IN
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-security/universe Translation-en
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-updates/main Sources
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-updates/restricted Sources
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-updates/universe Sources
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-updates/multiverse Sources
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-updates/main amd64 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-updates/restricted amd64 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-updates/universe amd64 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-updates/multiverse amd64 Packages
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-updates/main i386 Packages
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-updates/restricted i386 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-updates/universe i386 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-updates/multiverse i386 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-updates/main Translation-en_IN
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-updates/main Translation-en
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-updates/multiverse Translation-en_IN
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-updates/multiverse Translation-en
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-updates/restricted Translation-en_IN
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-updates/restricted Translation-en
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-updates/universe Translation-en_IN
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-updates/universe Translation-en
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-backports/main Sources
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-backports/restricted Sources
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-backports/universe Sources
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-backports/multiverse Sources
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-backports/main amd64 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-backports/restricted amd64 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-backports/universe amd64 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-backports/multiverse amd64 Packages
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-backports/main i386 Packages
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-backports/restricted i386 Packages
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-backports/universe i386 Packages
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-backports/multiverse i386 Packages
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-backports/main Translation-en_IN
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-backports/main Translation-en
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-backports/multiverse Translation-en_IN
Connection failed [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com precise-backports/multiverse Translation-en
Connection failed [IP: 91.189.91.15 80]
Err http://us.archive.ubuntu.com precise-backports/restricted Translation-en_IN
Connection failed [IP: 91.189.91.24 80]
Err http://us.archive.ubuntu.com precise-backports/restricted Translation-en
Connection failed [IP: 91.189.91.14 80]
Err http://us.archive.ubuntu.com precise-backports/universe Translation-en_IN
Connection failed [IP: 91.189.91.23 80]
Err http://us.archive.ubuntu.com precise-backports/universe Translation-en
Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/Release.gpg Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/Release.gpg Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release.gpg Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/Release.gpg Connection failed
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/Release.gpg Connection failed [IP: 216.58.220.46 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/Release.gpg Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/main/source/Sources Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/main/binary-amd64/Packages Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/main/binary-i386/Packages Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en_IN Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en Connection failed [IP: 91.189.92.152 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/Release.gpg Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/source/Sources Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/binary-amd64/Packages Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/binary-i386/Packages Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/i18n/Translation-en_IN Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/i18n/Translation-en Connection failed [IP: 91.189.92.191 80]
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/main/i18n/Translation-en_IN Connection failed
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/main/i18n/Translation-en Connection failed
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/main/i18n/Translation-en_IN Connection failed [IP: 216.58.220.46 80]
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/main/i18n/Translation-en Connection failed [IP: 216.58.220.46 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/Release.gpg Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/main/binary-amd64/Packages Connection failed
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/main/binary-amd64/Packages Connection failed [IP: 216.58.220.46 80]
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/main/binary-i386/Packages Connection failed
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/main/binary-i386/Packages Connection failed [IP: 216.58.220.46 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/source/Sources Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/source/Sources Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/source/Sources Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/source/Sources Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/binary-amd64/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-amd64/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-amd64/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/binary-amd64/Packages Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/binary-i386/Packages Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-i386/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-i386/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/binary-i386/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en_IN Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/i18n/Translation-en_IN Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/i18n/Translation-en Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/i18n/Translation-en_IN Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/i18n/Translation-en Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/i18n/Translation-en_IN Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/i18n/Translation-en Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/main/source/Sources Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/restricted/source/Sources Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/universe/source/Sources Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/multiverse/source/Sources Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/main/binary-amd64/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/restricted/binary-amd64/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/universe/binary-amd64/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/multiverse/binary-amd64/Packages Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/main/binary-i386/Packages Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/restricted/binary-i386/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/universe/binary-i386/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/multiverse/binary-i386/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/main/i18n/Translation-en_IN Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/main/i18n/Translation-en Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/multiverse/i18n/Translation-en_IN Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/multiverse/i18n/Translation-en Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/restricted/i18n/Translation-en_IN Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/restricted/i18n/Translation-en Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/universe/i18n/Translation-en_IN Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-security/universe/i18n/Translation-en Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/main/source/Sources Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/source/Sources Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/source/Sources Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/source/Sources Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/main/binary-amd64/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/binary-amd64/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/binary-amd64/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/binary-amd64/Packages Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/main/binary-i386/Packages Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/binary-i386/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/binary-i386/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/binary-i386/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/main/i18n/Translation-en_IN Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/main/i18n/Translation-en Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/i18n/Translation-en_IN Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/i18n/Translation-en Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/i18n/Translation-en_IN Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/i18n/Translation-en Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/i18n/Translation-en_IN Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/i18n/Translation-en Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/main/source/Sources Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/source/Sources Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/source/Sources Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/source/Sources Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/main/binary-amd64/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/binary-amd64/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/binary-amd64/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/binary-amd64/Packages Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/main/binary-i386/Packages Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/binary-i386/Packages Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/binary-i386/Packages Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/binary-i386/Packages Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/main/i18n/Translation-en_IN Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/main/i18n/Translation-en Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/i18n/Translation-en_IN Connection failed [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/i18n/Translation-en Connection failed [IP: 91.189.91.15 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/i18n/Translation-en_IN Connection failed [IP: 91.189.91.24 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/i18n/Translation-en Connection failed [IP: 91.189.91.14 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/i18n/Translation-en_IN Connection failed [IP: 91.189.91.23 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/i18n/Translation-en Connection failed [IP: 91.189.91.13 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
当我使用 cat gedit /etc/apt/sources.list 时，我得到以下信息：
答案1
仅凭这些信息很难判断哪里出了问题。你能访问其他网站吗？你用了代理吗？你试过了吗sudo apt-get clean？你也可以打开Software and Updates并从众多镜像中选择一个来下载更新。
如果您使用代理，请编辑或创建文件/etc/apt/apt.conf并插入您的代理设置：
Acquire::http::Proxy "http://<proxy_host>:<proxy_port>";
答案2
前段时间，一个使用 Linux Mint 13（基于 Ubuntu 12.04）的朋友遇到了同样的错误（网络可以访问，但所有存储库和镜像似乎都处于离线状态）...我几乎尝试了所有方法，但都没有用！
所以在我放弃之前的最后一件事是尝试取消选中所有来源（不要问我为什么），关闭，sudo apt-get update然后再次启用相同的来源，sudo apt-get update再次执行，一切都按应有的方式工作！
答案3
- 确保您已连接到互联网。
- 执行
sudo apt-get clean并sudo apt-get autoclean。现在，尝试再次进行更新。 - 如果这不起作用，请考虑安装
aptitude。