Past Imperfect (imparfait)

You can construct it by taking the present indicative nous form of any verb and replacing the -ons with the imperfect ending -ais -ais -ait -ions -iez -aient.

The only irregular imperfect verb is être, which takes on an ét- root but still follow the imperfect ending.

The imperfect (imparfait) describes situations, states of mind, and habits in the past. In a story, it sets the scene or background; thus, it often translates to and from the English past continuous tense (was/were going) or repeated actions or habits (used to, would).

We can translate using simple past tense for habits such as:

• Nous visitions chaque semaine. — We visited every week.
• À l'époque, elle chantait souvent. — Back then, she often sang.

or for stative verbs (to be, to think, to look, to smell, to understand):

• Il croyait son père. — He believed his father. (Not "was believing".)
• Nous avions trois cousins. — We had three cousins. (Using "were having" would make you a confessed cannibal.)

STATES OR SITUATIONS

To translate, use the English preterit (simple past) here to describe mental or physical conditions, scenes, date or times, weather, etc. (stative verbs).

ACTIONS OR PROCESSES

The continuous past can be used here to set up a scene by describing an action or process.

• Je marchais lentement. — I was walking slowly. 
• Vous regardiez la mer. — You were watching the sea.
• Elles pensaient à leurs enfants. — They were thinking of their children. ("Thinking" is a process here.)

Here are some irregular verbs that we should pay attention to:

ét-: to be. This is special, not forming from its present indicative nous form.

j'étais
tu étais
elle était
nous étions
vous étiez
ils étaient

Aller: to go. The present indicative nous form is nous allons. So the imparfait root is all-. So we have:

J'allais
Tu allais
elle allait
nous allions
vous alliez
ils allaient

Faire: to do, to make. The present indicative nous form is nous faisons. So the imparfait root is fais-.

Je faisais
tu faisais
il faisait
nous faisions
vous faisiez
ells faisaient

Avoir: to have. The present indicative nous form is nous avons. So the imparfait root is av-.

J'avais
tu avais
on avait
nous avions
vous aviez
ils avaient