Final answer:
The correct subjunctive sentence that expresses a negative opinion is: "Je ne pense pas qu'il publie bientôt un nouveau livre."
Step-by-step explanation:
The correct subjunctive sentence that expresses a negative opinion, thus an idea of doubt, is: Je ne pense pas qu'il publie bientôt un nouveau livre. This sentence translates to "I don't think he is publishing a new book soon." The use of "ne...pas" in the sentence indicates negation and uncertainty, conveying a negative opinion and doubt.
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