Réponse :
Mets ces verbes au prétérit simple ou au prétérit en be + V-ing selon la situation
BE + V-ing : action en cours dans le passé
prétérit simple : action courte qui vient interrompre une action en cours / succession de faits passés
a. She was reading a book when she heard a scream upstairs.
b. The monster was walking on the ice when Frankenstein saw him.
c. First, she heard a strange sound, then she listened carefully and she finally rushed to the bedroom. ( succession de faits )
d. When he discovered his portrait was aging, he panicked
