What verb tense is used for expressing simultaneous activities in the past? present imperfect preterit subjunctive

Explique por qué la teoría de la tectónica de placas resolvió los problemas con la hipótesis de la deriva continental.

Identify the three main regions of venezuela. la sierra andina patagonia los llanos la amazonía yucatán la guayana venezolana

When could you attach the direct object pronoun to an infinitive verb? a: when an infinitive verb follows a conjugated verb. b: when an infinitive verb ends in a question. c: when a stem-changing verb ends in a question. d: when a stem-changing verb follows a conjugated verb.