We need to fill the blanks with the verb ser or ir matching the corresponding conjugations. All these sentences stands for the imperfect tense. Recall that this tense is used to talk about past actions, conditions, or events that occurred regularly or frequently or that were in progress in a moment in the past.
(1) Eran
Since Anita y Jorge can be replaced by the subject pronoun for the third person plural ellos, then we need to use the conjugation either the verb ir or ser that matches the third person plural in the imperfect. The more logical verb to be used here is ser because they were young. So this conjugation is eran. Therefore:
Cuando Anita y Jorge eran jóvenes
(2) Eran
Here we continue to talk about Anita and Jorge, therefore we must use the verb ser conjugated as in the previous exercise eran. It is also important to say that we use the verb ser to talk about permanent or lasting attributes. In this way, this verb stands for descriptions, occupations, characteristics, time, origin and relationships.
Eran muy buenos amigos.
(3) Iban
In this problem, we need to use the verb ir because in this sentence Anita and Jorge used to go to school together. Thus, iban is the conjugation of the verb ir for the third person plural in the imperfect. This person is ellos. We use this subject pronoun when talking about masculine nouns or when talking about masculine and feminine nouns as a whole. So:
Ellos iban a la escuela juntos
(4) Iban
In this problem, we need to use the verb ir because in this sentence Anita and Jorge used to go to eat together. Here we also use the subject pronoun ellos. Therefore, we must use the conjugation that matches this subject pronoun, which is iban. Finally:
Ellos iban a comer juntos.
(5) era
Here we use the verb ser again conjugated as era because we are talking about Anita, that is, this sentence stands for the third person singular in the imperfect. So the verb ser stands for occupation here. Basically, it's what someone does for a living or as a hobby. Finally:
Anita no era muy buena alumna
(6) era
Here we use the verb ser again conjugated as era because we continue to talk about Anita. So this sentence also stands for the third person singular. So the verb ser also stands for occupation here because it describes what Anita used to do being a very good athlete. Finally:
pero era muy buena atleta.
(7) era
Here we use the verb ser again conjugated as era because we are talking about Jorge. So Jorge can be replaced by the subject pronoun for the third person singular, which is él. So this sentence also stands for the third person singular. Thus, the verb ser also stands for occupation here because it describes what Jorge used to be, that is, he was an excellent student. Finally:
Jorge era un excelente alumno
(8) era
Here we use the verb ser again conjugated as era because we continue to talk about Jorge. So this sentence also stands for the third person singular. Hence the verb ser also stands for occupation here because it describes that Jorge used to be a bad athlete. Finally:
pero no era buen atleta.
