The passé composé form 'as envoyé' completes the sentence correctly.
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.
https://brainly.com/question/40417113