The past progressive tense (imparfait) is used for ongoing actions in the past. For regular -er verbs, you would use the imperfect tense to express past continuous actions.
Here's how you would conjugate "conjuguer" in the imperfect tense:
* Je conjuguais
* Tu conjuguais
* Il/Elle/On conjuguait
* Nous conjuguions
* Vous conjuguiez
* Ils/Elles conjuguaient
For example:
* Je conjuguai le verbe "aimer" en classe. (I was conjugating the verb "to love" in class.)
* Ils conjuguaient les verbes irréguliers. (They were conjugating irregular verbs.)