1. The imperfect is used to talk about the past, but it has different uses than the preterite. The imperfect tells what someone used to do, what things were like, or how things used to be.
2. Form the imperfect by removing the -ar, -er, or -ir infinitive ending and adding the imperfect endings below. Note that the yo and él/ella/usted forms are the same. Context makes it clear who the subject is.
nosotros, nosotras nos ayudamos we help each other vosotros, vosotras os ayudáis you help each other ustedes se ayudan you help each other ellos, ellas se ayudan they help each other
The rules for the placement of these pronouns are the same as those for reflexive pronouns.