Final answer:
The dependent clause in the provided sentence is 'that he thought would look perfect with his superhero costume,' as it cannot stand on its own and relies on the main sentence for its meaning.
Step-by-step explanation:
The words that make up the dependent clause in the sentence 'Spiderman bought a pair of boots that he thought would look perfect with his superhero costume' are 'that he thought would look perfect with his superhero costume.' This clause cannot stand alone as a complete sentence and relies on the main clause to provide context and completeness.
An easy way to identify a dependent clause is to look for subordinating conjunctions. Although the given sentence doesn't start with a subordinating conjunction, the word 'that' is a relative pronoun that introduces the dependent clause, indicating extra information about the boots Spiderman bought.
A dependent clause has a subject and a verb; in this case, 'he' is the subject, and 'thought' is the verb. However, since it cannot stand alone as a full sentence, it depends on the rest of the sentence to make sense.