Final answer:
The correct verb to fill in the blank is 'Hace', which expresses the length of time in Spanish.
Step-by-step explanation:
The correct answer to fill in the blank in the sentence tres años que hablo español is Hace.
Step-by-step explanation:
In Spanish, the verb hace is used to express the length of time that has passed since an action started. It is followed by a period of time, in this case, tres años (three years).
Example:
Hace cinco meses que estudio inglés. (I have been studying English for five months.)
Learn more about Spanish verbs