Final answer:
The passé composé form 'as envoyé' completes the sentence correctly.
Explanation:
The correct form of the passé composé to complete the sentence 'Tu des cartes postales à tes amis.' is 'as envoyé.' The passé composé is used with completed actions in the past. In this case, 'as envoyé' signifies 'you sent' postcards to your friends.
Learn more about Past Tense in French here:
https://brainly.com/question/40417113
