命中:1 http://security.ubuntu.com/ubuntu focal-security InRelease
命中:2 http://us.archive.ubuntu.com/ubuntu focal InRelease
命中:3 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
命中:4 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
正在读取软件包列表... 完成
在终端内分别输入以下五句命令即可
sudo apt-get clean
sudo mv /var/lib/apt/lists /tmp
sudo mkdir -p /var/lib/apt/lists/partial
sudo apt-get clean
sudo apt-get update