Final answer:
The provided sentence is correct in its use of the imperfect verb form.
Step-by-step explanation:
The subject of this question is Spanish. The sentence provided, 'La maestra estaba en la escuela', is written in the imperfect form of the verb 'estar' (to be). The use of the imperfect form here is correct, as it indicates an ongoing action or a state of being in the past.
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