Final answer:
The correct form of the imperfect tense verb 'gustar' is 'gustaban' and it agrees with the subject 'a Fernando' in the sentence.
Step-by-step explanation:
The correct form of the imperfect tense of the verb 'gustar' to complete the sentence is 'gustaban'.
Here, the subject is 'a Fernando' and the verb 'gustar' is conjugated to agree with it. Since 'a Fernando' is singular, the correct form is 'gustaba'.
Therefore, the complete sentence should be: En las celebraciones del año 2007, a Fernando nunca le gustaban la letra de las canciones.
Learn more about Spanish verb conjugation