Emergency
Who done it?
We have seen sentences where on means we, like On va au cinéma. But you can also use on when you don't know who did the action!
On a volé mon vélo !
My bicycle was stolen! (Literal: One stole my bicycle.)
Je suis furieux parce qu'on a volé ma voiture.
I'm furious because my car was stolen. (Literal: I'm furious because one stole my car.)
Mixing it up
You can use both the imparfait and the passé composé in the same sentence. The imparfait describes the background info, and the passé composé describes what happened!
Nous faisions les devoirs quand notre mère est rentrée.
We were doing our homework when our mother came home.
Il y avait beaucoup de monde dans le magasin quand elle est entrée.
There were a lot of people in the store when she came in.
Tu pleurais encore quand je suis arrivée.
You were crying when I arrived.
J'ai vu quelque chose d'intéressant
If you want to say things like something interesting or something funny in French, say quelque chose de, followed by an adjective.
Elle nous a raconté quelque chose de drôle.
She told us something funny.