sudo sed -i '1i deb https://mirrors.ustc.edu.cn/kali kali-rolling main non-free non-free-firmware contrib' /etc/apt/sources.list
sudo sed -i '1i deb-src https://mirrors.ustc.edu.cn/kali kali-rolling main non-free non-free-firmware contrib' /etc/apt/sources.list
sudo apt-get update