I believe that "I don't think I can finish." is an independent clause. An independent clause is a sentence. Jim studied in the Sweet Shop for his chemistry quiz. Dependent Clause. A dependent clause is a group of words that contains a subject and verb but does not express a complete thought. A dependent clause cannot be a sentence. "I don't think I can finish," is a complete sentence. It has a verb, finish, and a subject, I.
Hope this helps! :)