Final answer:
The given sentence is grammatically correct: 'El profesor pensaba que tú eras un buen estudiante.' The subject of this question is Spanish, and it is at a High School level.
Step-by-step explanation:
The given sentence is grammatically correct: El profesor pensaba que tú eras un buen estudiante. It translates to 'The professor thought that you were a good student.' In this sentence, 'El profesor' is the subject, 'pensaba' is the verb, 'que tú eras un buen estudiante' is the subordinate clause, and 'eras un buen estudiante' is the predicate. The sentence follows the correct word order and uses appropriate verb conjugation and agreement.
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