摘自百度贴吧，留存

http://mirrors.ustc.edu.cn/ubuntu-ports/
http://ftp.ubuntu-tw.org/mirror/ubuntu-ports/
http://mirror.csclub.uwaterloo.ca/ubuntu-ports/
http://mirrors.mit.edu/ubuntu-ports/

速度从上到下越来越慢 中科技大 > *新北 > 滑铁卢大学 > 麻省理工学院
/etc/apt/source.list 手动替换里面的地址吧

还有国外的两个

deb http://mirrors.mit.edu/ubuntu-ports/ trusty main restricted universe multiverse 
deb http://mirrors.mit.edu/ubuntu-ports/ trusty-updates main restricted universe multiverse 
deb http://mirrors.mit.edu/ubuntu-ports/ trusty-security main restricted universe multiverse 
deb http://mirrors.mit.edu/ubuntu-ports/ trusty-backports main restricted universe multiverse 
deb http://mirror.csclub.uwaterloo.ca/ubuntu-ports/ trusty main restricted universe multiverse 
deb http://mirror.csclub.uwaterloo.ca/ubuntu-ports/ trusty-updates main restricted universe multiverse 
deb http://mirror.csclub.uwaterloo.ca/ubuntu-ports/ trusty-security main restricted universe multiverse 
deb http://mirror.csclub.uwaterloo.ca/ubuntu-ports/ trusty-backports main restricted universe multiverse