theories in Portal

PART 2 of my theory.
So after the combine invasion ends, in America could've happend the Green Flu, that made people into "zombies", and that happend in America and who knows where else. But after the pandemic ends, millenias later Portal 2 happends.

PART 1
So i have a theory that L4D, Half Life and Portal series are all connected to eachover. So my theory goes like that:
Half Life 1 happends and 20 years later Portal 1 and Half Life 2 happends, after the combine invation ends the world is free.

PORTAL THEORY: PART 2

If the lyrics of the song Cara Mia Addio are in Italian. I could not put the song in this, as it. Has to many letters, but this could mean GLaDOS made the turrets sing in Italian so chell could understand.