The imperfect tense describes something one 'used to do'. It is less specific than the perfect tense, which describes a specific action taking place at a specific time, and is used to describe more general actions in the past. For example 'I used to play tennis' is the imperfect, whereas 'Last Wednesday, I played tennis' is the perfect. In order to conjugate the imperfect tense, take the 'nous' form of the verb and remove the -ons suffix. Then, add one of the folllowing endings accoridng to the subject of the sentence:je -aistu -aisil/elle -aitnous -ionsvous -iezils/elles -aient