Imperfect Tense

This past tense corresponds to "was, were or used to."  This tense is
used for repeated, continuous, or ongoing actions; as well as for verbs that
describe background and circumstances, such as weather, time, and physical,
mental, and emotional states.  Use the passé composé for
actions that happened once and are done.  However, verbs that express
mental and emotional states that are descriptive in nature are generally
used in the imperfect in a past context.  These verbs are: aimer,
avoir, croire, détester, espérer, être, penser, and

préférer.

To form the stem, use the nous form of the present tense and drop the -ons.
 Then add these endings:

-ais	-ions
-ais	-iez
-ait	-aient

The only exception is être in which you must use the stem
ét-, but still the same endings.  Verb stems that end
in -c must use a cedilla (ç) under the c to make it soft. Verbs stems
endings in -g keep the e before all forms except nous and vous.

être
étais	ay-teh	étions	ay-tee-ohn
étais	ay-teh	étiez	ay-tee-ay
était	ay-teh	étaient	ay-teh

commencer					manger
commençais	koh-mawn-seh	commencions	koh-mawn-see-ohn		mangeais	mawn-zheh	mangions	mawn-zhee-ohn
commençais	koh-mawn-seh	commenciez	koh-mawn-see-ay		mangeais	mawn-zheh	mangiez	mawn-zhee-ay
commençait	koh-mawn-seh	commençaient	koh-mawn-say		mangeait	mawn-zheh	mangeaient	mawn-zhay

Avoir, Devoir, Pouvoir, Savoir, and Vouloir

These verbs change meanings, according to whether they are used in the imperfect
or the passé composé.

	Imperfect		Passé Composé
avoir	j'avais	I had	j'ai eu	I got, received
devoir	je devais	I was supposed to	j'ai dû	I must have, I had to (and did)
pouvoir	je pouvais	I was capable	j'ai pu je n'ai pas pu	I was able to (and did), succeeded I couldn't, failed
savoir	je savais	I knew	j'ai su	I found out, discovered
vouloir	je voulais	I wanted to	j'ai voulu je n'ai pas voulu	I tried, decided, insisted I refused

The imperfect tense is also used with these constructions:

être en train de + infinitive
J'étais en train d'étudier quand vous êtes arrivés.	I was (in the process of ) studying when you arrived
aller + infinitive
J'allais sortir quand le téléphone a sonné.	I was going to leave when the phone rang.
venir de + infinitive
Je venais de manger, alors je n'avais plus faim.	I had just eaten, so I wasn't hungry anymore.

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This article was used with permission from:
Indo-European Languages