As

De Linuxmemo.

Quand 2 choses arrive en meme temps

I watched her as she opened the door.
turn off the lights as you go out.

"Just as" au moment exact

John arrived, just as i left.
I had toleave just as the conversation was getting interesting.

Raison (because)

As i was feeling tired, I went to bed early.
As they live near us, we see them quite often

Comme (quelqu'un ou quelque chose)

A few years ago i worked as a teacher
We use the garrage as a workshop

As if (comme si) to say how someone looks/sounds/feels

Kelly sounds as fi she's got a cold.
The house looked as if nobody lived in it.

Pour dire comment ce passe quelque chose

He ran as if he never running for his life.
After interruption, she contined talking as if nothing had happend