Final answer:
The appropriate verb form to fill the blank is 'está', which means 'is' in English.
Step-by-step explanation:
The appropriate verb form to fill in the blank in the sentence is está. The sentence translates to 'The teacher is always tired.' Here, 'La profesora' is the subject, which means 'The teacher' in English. Since the subject is third person singular, we use the verb form 'está', which means 'is' in English.
Learn more about verb forms in Spanish