Preterite is the normal past tense talking about events. Eg i went to the park with my sister = Fui al parque con mi hermana.
Fui in this case is the preterite
For imperfect it is what you used to do before but do not do any more. Usually ends in
aba
abas
aba
abamos
abais
aban
(for ar endings)
A direct object pronoun replaces a direct object, that is a noun that directly receives the action of a verb in a sentence. Moreover, direct object pronouns in Spanish agree in number and gender with the nouns they replace. In the sentence:
<em>Compro </em><em>la gasolina </em><em>en la estación de servicio</em>
<em>La gasolina</em> is the direct object because it receives the action comprar. Since <em>la gasolina </em>stands for the third person singular in feminine form, we need to use the direct object pronoun that matches this person, that is, la. Therefore, the new sentence is:
<em>La </em><em>compro en la estación de servicio</em>
