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
# 修改系统源 sudo vi /etc/apt/sources.list.d/raspi.list
deb http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ stretch main ui deb-src http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ stretch main ui