Bob drives carefully . (Carefully modifies the verb drives.)
Bob drives very carefully. (Very modifies the adverb carefully.)
Bob is quite tall. (Quite modifies the adjective tall.)
again, ago, all, almost, also, always, any, anyhow, anymore, anyplace, anytime, anyway, anywhere, better, best, enough, far, farther, fast, further, furthest, here, how, inside, just, later, maybe, more, most, much, never, next, now, often, once, outside, quite, rather, slow (also slowly), so, some, somehow, sometime, sometimes, somewhat, still, straight, there, therefore, too, very, well, what, whatever, when, whence, whenever, where, whereby, wherein, wherever, yet.
friendly, likely, lonely, and lovely are adjectives.
Early can be an adjective OR an adverb.
Sara walks fast. (adverb) = Sara is a fast walker. (adjective).
The early bus (adjective) = the bus that arrives early (adverb).
Some adverbs are irregular:
far--farther (further)--farthest (furthest).