How to fix updating ubuntu apt-get problem

It‘s my new PC with a new os of ubuntu.

every time when I want to install software or update apt-get, this error will appear:

First, as the most usual functions the website given:

to type these commands:

sudo rm /var/lib/apt/lists/* -vf
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade

But not worked.

Finally, I reset the system settings:

See,"download from xx."

fix it from US‘s  to this.

then it worked.

How to fix updating ubuntu apt-get problem

原文：http://www.cnblogs.com/rixiang/p/5879797.html