m_wlliam:

把这些都放进去试试，我的就下载好了：deb https://mirrors.ustc.edu.cn/ubuntu/ questing main restricted universe multiverse

deb-src https://mirrors.ustc.edu.cn/ubuntu/ questing main restricted universe multiverse

deb https://mirrors.ustc.edu.cn/ubuntu/ questing-security main restricted universe multiverse

deb-src https://mirrors.ustc.edu.cn/ubuntu/ questing-security main restricted universe multiverse

deb https://mirrors.ustc.edu.cn/ubuntu/ questing-updates main restricted universe multiverse

deb-src https://mirrors.ustc.edu.cn/ubuntu/ questing-updates main restricted universe multiverse

deb https://mirrors.ustc.edu.cn/ubuntu/ questing-backports main restricted universe multiverse

deb-src https://mirrors.ustc.edu.cn/ubuntu/ questing-backports main restricted universe multiverse

## Not recommended

# deb https://mirrors.ustc.edu.cn/ubuntu/ questing-proposed main restricted universe multiverse

# deb-src https://mirrors.ustc.edu.cn/ubuntu/ questing-proposed main restricted universe multiverse