我正在尝试运行一个sudo apt-get update命令，我当前的发行版是 Debian Wheezy，当我尝试运行该命令时出现此错误：
W: Failed to fetch http://security.debian.org/dists/wheezy/updates/Release
Unable to find expected entry 'main/binary-mipsel/Packages' in Release file
(Wrong sources.list entry or malformed file)
但是，当我查看sources.list文件时，它似乎没问题：
deb http://http.debian.net/debian wheezy main
deb-src http://http.debian.net/debian wheezy main
deb http://http.debian.net/debian wheezy-updates main
deb-src http://http.debian.net/debian wheezy-updates main
deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main