Final answer:
The subject of this question is Spanish, and the student is asking for help in completing a sentence in Spanish.
Step-by-step explanation:
The subject of this question is Spanish. The phrase 'Juanito, tú nunca me ayudas. ¡Siempre tengo que ______ la cena yo sola!' translates to 'Juanito, you never help me. I always have to ______ dinner on my own!'. Based on the context, it is likely that the missing word is a verb that means 'prepare' or 'make' in Spanish.
Learn more about Spanish verb conjugation