每当我尝试通过软件更新程序更新 ubuntu 16.04 时，我都会收到一条错误消息，提示“无法下载存储库信息。请检查您的互联网连接”。我尝试了网上找到的几种方法，但都不起作用。
这是我grep -E '^\w' /etc/apt/sources.list在终端输入后得到的结果。
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety main restricted
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety main restricted
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates main restricted
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates main restricted
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety universe
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety universe
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates universe
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates universe
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety multiverse
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety multiverse
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates multiverse
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-updates multiverse
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-backports main restricted universe multiverse
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-backports main restricted universe multiverse
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security main restricted
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security main restricted
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security universe
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security universe
deb http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security multiverse
deb-src http://archive.ubuntu.mirror.rafal.ca/ubuntu/ yakkety-security multiverse