ellos mostraban

were showing

→ mostrar
mostr show + aban 3rd-person plural imperfect (indicative or subjunctive)
verb · third plural · imperfect indicative Rare #38,647
were showing Imperfect tense (they/you all were showing); can describe an ongoing or repeated action in the past.
SP: En el museo, los guías mostraban las pinturas a los visitantes.
EN: At the museum, the guides were showing the paintings to the visitors.
Conjugation of mostrar
Indicative imperfect
SingularPlural
Third — mostraban
Subjunctive imperfect
SingularPlural
Third — mostraban

Sus vestidos mostraban casi la mayoría de los tonos del arcoíris.

Their dresses displayed almost all the colors of the rainbow.

Los secuestradores no mostraban señales de ceder.

The kidnappers showed no signs of giving up.

Los rayos X no mostraban nada, porque esa cosa no tenía huesos.

The X-rays weren't showing anything because that thing didn't have any bones.

— El síndrome asténico (1989)

Mostraban preocupación.

They showed concern.

Los participantes mostraban la misma actividad cerebral.

The participants showed the same brain activity.

Sus ojos mostraban una gran tristeza.

Her eyes showed great sadness.