Réponse :
I) 1 started
2 were gathering
3 were taking
4 were
5 became
6 had
II) didn't start
weren't gathering
weren't taking
weren't
didn't become
didn't have
III) has again become
On utilise le present perfect car c'est une action qui a commencé dans le passé et qui est encore en progression au moment où l'on parle.
IV) il n'y a pas d expression souligné
Explications :