Passé composé et l'imparfait
working of this pair of past tenses in combination can pose serious
problems for the learners of French. This is because the choice
depends primarily upon the emphasis decided by the speaker, rather
than a definite grammatical rule. This page describes the general
functions of these tenses and shows
their use can be flexible in many instances.
Valeurs générales du Passé composé et de l'Imparfait