Final answer:
The correct pair of verbs is 'veía, escribía'.
Step-by-step explanation:
The correct pair of verbs to complete the sentence is veía, escribía. The subject of the sentence is 'mientras yo veía la televisión'. In Spanish, when we use the verb 'ver' (to watch/see) in the imperfect tense, we use 'veía' for the first-person singular. And when we use the verb 'escribir' (to write) in the imperfect tense, we use 'escribía' for the third-person singular.
Learn more about Spanish verb conjugation