Final answer:
In the sentence 'I was nervous,' nervous is an adjective. In the sentence 'I nervously picked at my fingernails,' nervously is an adverb.
Step-by-step explanation:
In the sentence 'I was nervous,' nervous is an adjective because it describes the noun 'I'.
In the sentence 'I nervously picked at my fingernails,' nervously is an adverb because it describes the verb 'picked'.
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