In our imparfait formation lesson, the stem always came from the nous form of the présent. Être is the one common verb that breaks this rule, "nous sommes" minus "-ons" would give "somm-", but the real stem is ét-.
1. The irregular stem: ét-
| J'étais fatigué. | I was tired. |
| Tu étais où ? | Where were you? |
| C'était génial ! | It was great! |
2. Still the regular endings
Once you have the stem ét-, everything else is completely regular, the same -ais, -ais, -ait, -ions, -iez, -aient as every other verb.
3. A classic use: il était une fois
Fairy tale French: il était une fois ("once upon a time") uses the imparfait because it sets the scene, a background state, exactly the kind of thing this tense is built for. More in our imparfait usage lesson.
4. Conjugation: être
| j'étais | I was |
| tu étais | you were |
| il / elle / on était | he / she / one was |
| nous étions | we were |
| vous étiez | you were |
| ils / elles étaient | they were |