Final answer:
The sentence "El niño leía el libro" is correct. The verb "leía" is in the imperfect form and means "was reading".
Step-by-step explanation:
The given sentence: "El niño leía el libro" is correct. This sentence is in the imperfect tense, which is used to describe ongoing or repeated actions in the past. In this case, the verb "leía" is the imperfect form of the verb "leer", meaning "to read". The imperfect tense is commonly used in narrative writing or to provide background information.
Learn more about Imperfect tense in Spanish verbs