Final answer:
The imperfect form of the verb in the sentence is correct.
Step-by-step explanation:
The imperfect form of the verb in the sentence Éramos una hermosa tarde de verano is correct as written.
In Spanish, the imperfect tense is used to describe ongoing or habitual actions in the past.
In this sentence, the verb éramos is the imperfect form of the verb ser, which means 'to be.' It is correctly conjugated to match the subject pronoun nosotros (we).
Learn more about Spanish verb conjugation