The direct object pronoun would be "la" because la gasolina is feminine. In a sentence you could say
La compro en la estacion de servicio.
Direct object pronouns are placed before the verb generally.
Hacer means "to do" and is regular in every conjugation except in the "yo" form.
6. Sirvan el maiz.
7. Olmec
8. A large canyon
9. durazno
10. vaya a casa
