Here are the completed sentences with the correct preterite forms of "ir" and "ser":
- Ayer fue un día bueno para nosotros.
- Primero, yo fui a la estación de servicio para llenar el tanque con gasolina.
- Luego Fernando y yo fuimos a la tienda de equipo deportivo para mirar patines.
- Nuestras amigas Teresa y Patricia fueron al almacén.
- En la noche todos nosotros fuimos al cine. La película fue muy cómica.
Question 2:
For #2 above, the verb used is "IR." This can be determined because the action described involves going to a location, which is the essence of the verb "ir" (to go). In this case, the sentence describes the speaker's action of going to a gas station to fill up the gas tank, indicating movement toward a place.
Question 3:
For #5 above, the verb used is "SER." This can be determined because the sentence is not describing movement but rather giving a description of the movie, which is an attribute. "Fue" (was) is used here to indicate that the movie was comic, serving as a characteristic of the movie rather than indicating movement to a location.