Imperfect or preterite? One way this pair of tenses is often used is to talk about an ongoing action or event that was interrupted in the past. In such case, the interrupted action is given in the imperfect tense, while the interrupting action is given in the preterite. For example: Iba por la calle cuando me encontré a Laura (I was walking down the street (imperfect in Spanish) when I met Laura (preterite). / Estaba durmiendo cuando me llamaste - I was sleeping (imperfect in Spanish) when you called me (preterite).