Answer:
1. Cuando mis padres eran novios, vivían en pueblos diferentes.
2. A Diego Rivera le gustaba pintar murales.
3. Ella era de una familia distinguida de la capital.
4. El hombre creyó que la mujer decía la verdad.
5. Había mucha gente en el supermercado.
6. Cuando éramos niños jugábamos a ser famosos.
Explanation:
The imperfect in Spanish is used to talk about past events which don’t have a precise beginning or end or that have certain continuity. The preterite is used as the simple past is used in English: to refer to past events that begin and end in the past. In this exercise all the sentences except one are in the imperfect. Some refers to habits in the past, as de Diego Rivera example (1), and the kids playing during their childhood (6). Others talk about indefinite moments in the past, where the duration is either non important or imprecise (examples 1, 3, 5). In the case of sentence number 4, both the imperfect and the preterite could be used depending on the context of the sentence but it’s better to use the preterite: the man thought the woman was telling the truth. At that moment, he believed she was being honest. Her action is in the imperfect whereas his is in the preterite.