Rule 1. Many adverbs end in -ly, but many do not. Generally, if a word can have -ly added to its adjective form, place it there to form an adverb. Quick is an adjective describing thinker, so no -ly is attached. read more
An adverb is a word that is used to change or qualify the meaning of an adjective, a verb, a clause, another adverb, or any other type of word or phrase with the exception of determiners and adjectives that directly modify nouns. read more