Answer:
be the same part of speech
Explanation:
Parallelism consists in using words, phrases or clauses with an identical grammatical form. Therefore, for a series of three or more items to be a parallel structure, they must be the same part of speech.
e.g. "My favorite camping activities are fishing, hiking, and swimming."
This sentence uses three gerunds <em>fishing, hiking, </em>and <em>swimming</em> as predicative nouns. This is correct parallel structure.
