The main clause that indicates the subordinate second clause will need to be in the subjunctive is "Es dudoso que...".
Explanation:
1. In Spanish, when the main clause expresses doubt, uncertainty, denial, disbelief, or something subjective, the subordinate clause that follows it typically requires the use of the subjunctive mood.
2. The phrase "Es dudoso que..." translates to "It is doubtful that..." or "It is questionable that..." which conveys uncertainty, making it necessary to use the subjunctive in the following clause.
Therefore, when you see "Es dudoso que..." as the main clause, you should expect the subordinate second clause to be in the subjunctive mood in Spanish.
