Debian9如何解决apt-get ｕｐｄａｔｅ提示错误

1.输入该命令按回车键：cd /etc/apt

2.mv sources.list sources.list.back，输入该命令按回车键

3.输入该命令按回车键：vi sources.list

4.按“i”进入插入模式，输入以下内容，然后按“ESC”键输入wq按回车键保存退出vi编辑

deb http://archive.debian.org/debian stretch maindeb-src http://archive.debian.org/debian stretch maindeb http://archive.debian.org/debian-security stretch/updates maindeb-src http://archive.debian.org/debian-security stretch/updates main

5.输入该命令按回车键可以正常执行：apt-get ｕｐｄａｔｅ -y