HOla Elliot, IN a nutshell, you use the IMPERFECT for things that happened -repeatedly in the past -to say "I used to/I would..." -to say "I was...." , a continuous action in the past -also for expressing beliefs, emotions and desires You use the PRETERITO for actions -that are completed in the past -with a definite time frame -actions that happened once, were completed immediately. As for yuor answers: I’m having trouble with the Preterite and Imperfect in Spanish. He lived in Costa Rica – Preterite YES (viví) He was living in Costa Rica – Imperfect YES (vivía/estaba viviendo) He spoke to my sister – Preterite YES(habló) He used to speak to my sister – Imperfect YES (le hablaba) He was speaking to my sister – Imperfect YES (estaba hablando) She thought that we were friends – Imperfect YES (pensaba/eramos) I wanted that car – IMPERFECT because it is a desire/wish (quería) Quise ese coche o quería ese coche? You can use 'quise' in the sentence "Siempre quise ese carro" = I've always wanted that car/I always wanted that car. If you just use quise, then it means that in the past you wanted that car but never got it. Hope that helps.