
Andrew L. answered 01/27/19
English and ESL tutor with 16 Years of Tutoring Experience
One reason for this is that they could be separated by the preposition “that.” Another way to look at this is to think of “I think” as modifying the primary verb (e.g., drive or go). It expresses a level of doubt or uncertainty, creating the subjunctive mood.
Hipe pe this helps,
Andy