La voix active is when the subject does the action, instead of receiving the action. In this case all you have to do switch the object and the subject, and change the verb tense from passé surcomposé to passé composé.
The first one becomes : Ils ont réparé ma voiture.
The second one : Mon fils a perdu son chat.
You see that there's one past participate that is remove and the sentence seems to be flip (kinda). Also, sometime you have to make up the subject since it's not explicit like in number 1.
3 Le technicien a réparé notre ordinateur.
4. Ici, nous avons vendu du café.
5. Nous avons ouvert la porte ce matin.
6. Nous avons fermé les livres.
7 Le prof a corrigé ma composition.
8. Ils ont bâti la maison en 1955.
Hello
2. Ce sont les papiers des étudiants
Byye
To further the plot of the show. Honestly, I am hoping that in season two they finally figure out each other's identities because this is getting ridiculous. I'm hoping the reason Marinette and Adrian can't tell each other's identities has to do with the magic of the miraculous. So that you would only know the other person's identity if they told you. Otherwise it wouldn't really make sense how they (and the rest of Paris) couldn't put the clues together.
