Ella ___ (estar) caminando cuando ___ (caerse).

Answer explanation

was walking - 1st action happening is imperfect

fell - 1 time event overlapping 1st action

Mis hermanos ___ (ver) la televisión mientras mi mamá ___ (cocinar) la cena.

Answer explanation

simultaneous actions, both imperfect

___ (Empezar) a llover cuando nosotros ___ (jugar) al voleibol.

Answer explanation

first action happening needs imperfecto, playing

action interrupting or overlapping needs pretérito - it can only start raining once

Mi padre ___ (cocinar) mientras mi madre ____ (poner) la mesa.

Answer explanation

simultaneous actions, both need imperfecto

Cuando el terremoto (earthquake) ___ (ocurrir), yo ___ (estar) durmiendo.

Answer explanation

first action happening needs imperfecto - was sleeping

second action interrupting needs pretérito - earthquake happened 1 time

Cuando era niña, a mí ___ (encantar) cantar mientras mi padre ___ (tocar) la guitarra.

Answer explanation

simultaneous actions, both need imperfect.

Encantar is a gustar like verb that needs IOP and only has 2 conjugations

¡Qué hora ___ cuando llegaste? (ser)

Answer explanation

time, identifying time - imperfecto

Ellos ___ todo el pastel anoche. (comerse)

Answer explanation

1 time event needs preterito.

Don´t forget reflexive pronouns

Miguel ___ 17 años (tener) cuando ___ la verdad (saber).

Answer explanation

age needs imperfecto.

Saber in the preterite means to find out - you can find out the truth 1 time.

Sus bisabuelos ___ carpinteros cuando eran jóvenes. (ser)

Answer explanation

profession in the past is preterite.

This is not a descrition.