$ sudo nano /etc/apt/sources.list deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi deb http://mirrors.neusoft.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi deb-src http://mirrors.neusoft.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi