Почему я не могу установить Latex в ubuntu 12.04? [Дубликат]

Когда я запустил $ sudo apt-get install texlive-latex-base, он показал следующую ошибку.

Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  libgraphite3 libkpathsea6 libptexenc1 libreadline5 libruby1.8 lmodern luatex
  ruby ruby1.8 tex-common texlive-base texlive-binaries texlive-common
  texlive-doc-base texlive-latex-base-doc texlive-luatex
Suggested packages:
  ri ruby-dev ruby1.8-examples ri1.8 perl-tk
The following NEW packages will be installed:
  libgraphite3 libkpathsea6 libptexenc1 libreadline5 libruby1.8 lmodern luatex
  ruby ruby1.8 tex-common texlive-base texlive-binaries texlive-common
  texlive-doc-base texlive-latex-base texlive-latex-base-doc texlive-luatex
0 upgraded, 17 newly installed, 0 to remove and 0 not upgraded.
Need to get 35.0 MB/102 MB of archives.
After this operation, 201 MB of additional disk space will be used.
Do you want to continue [Y/n]? Y
Err http://ppa.launchpad.net/texlive-backports/ppa/ubuntu/ precise/main lmodern all 2.004.1-5~precise1
Connection failed
Err http://ppa.launchpad.net/texlive-backports/ppa/ubuntu/ precise/main texlive-binaries i386 2012.20120628-1~ubuntu12.04.1
Connection failed
Failed to fetch http://ppa.launchpad.net/texlive-backports/ppa/ubuntu/pool/main/l/lmodern/lmodern_2.004.1-5~precise1_all.deb  Connection failed
Failed to fetch http://ppa.launchpad.net/texlive-backports/ppa/ubuntu/pool/main/t/texlive-bin/texlive-binaries_2012.20120628-1~ubuntu12.04.1_i386.deb  Connection failed
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Я также попытался $ sudo apt-get install --fix-missing texlive-latex-base, который показал ошибку

naveen@naveen-Inspiron-3521:~$ sudo apt-get install --fix-missing texlive-latex-base
[sudo] password for naveen: 
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
lmodern luatex tex-common texlive-base texlive-binaries texlive-common
texlive-doc-base texlive-latex-base-doc texlive-luatex
Suggested packages:
perl-tk
The following NEW packages will be installed:
lmodern luatex tex-common texlive-base texlive-binaries texlive-common
texlive-doc-base texlive-latex-base texlive-latex-base-doc texlive-luatex
0 upgraded, 10 newly installed, 0 to remove and 0 not upgraded.
Need to get 48.2 MB/87.6 MB of archives.
After this operation, 169 MB of additional disk space will be used.
Do you want to continue [Y/n]? y
Err http://archive.ubuntu.com/ubuntu/ precise/main texlive-binaries i386 2009-11ubuntu2
Connection failed [IP: 91.189.92.201 80]
Err http://archive.ubuntu.com/ubuntu/ precise/main texlive-latex-base-doc all 2009-15
Connection failed [IP: 91.189.91.13 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/t/texlive-bin/texlive-binaries_2009-11ubuntu2_i386.deb  Connection failed [IP: 91.189.92.201 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/t/texlive-base/texlive-latex-base-doc_2009-15_all.deb  Connection failed [IP: 91.189.91.13 80]
Unable to correct missing packages.

    E: Aborting install.

Как я могу избавиться от этой проблемы?