UBUNTU 15.04 apt-get update失败

Chip Platform Rockchip
1

出现错误：E: Some index files failed to download. They have been ignored, or old ones used instead
参考网上换了阿里的镜像也不行

2

应该还是源不行，换清华的源试试，我都是用的清华的源
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-updates main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-updates main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-security main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-security main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-backports main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid-backports main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid main universe restricted
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ vivid main universe restricted

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-updates main restricted universe multiverse
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-updates main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-security main restricted universe multiverse
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-security main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-backports main restricted universe multiverse
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid-backports main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid main universe restricted
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ vivid main universe restricted

3

谢谢，弄半天市面上的163 阿里 搜狐 都不行，只有清华的可以；