Read the following sentence. Studying glassblowing has to be one of the most interesting subjects ever! Classify the underlined group of words.

"Studying glassblowing" is a gerund. A gerund adds - ing to the end of a verb and sets it in context of a subject.

"Has to" is the verb in this context. Then the object would the "one." The phrases following "one" are adjectives describing "one."