a) we couldn't (were not allowed to) chat on the Internet but we could (were allowed to) call our parents and friends
b) we could (were allowed to) watch tv but we could't (weren't allowed to) go to the pub
c) we couldn't (were not allowed to) stay up late but we could (were allowed) to play
video games one hour per day
tu n'as pas précisé quel auxilliaire modal il fallait utilisé, ni à quel tps (si c'est au présent, il faut changer could en can et were en are..... Il y a d'autre solutions et tu peux aussi "mixer" ; ex : we could (can) but we weren't allowed to....tout dépend de ton cours....
en espérant avoir aidé un peu
