deb http://mirrors.163.com/ubuntu/ bionic main universe
deb http://mirrors.163.com/ubuntu/ bionic-updates main universe
deb http://mirrors.163.com/ubuntu/ bionic-proposed main universe
deb http://mirrors.163.com/ubuntu/ bionic-backports main universe
deb http://mirrors.163.com/ubuntu/ bionic-security main universe

# deb http://security.ubuntu.com/ubuntu bionic-security main universe

# deb http://archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse
# deb http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
# deb http://archive.ubuntu.com/ubuntu/ bionic-proposed main restricted universe multiverse
# deb http://archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse