Regular comparative and superlative forms
|with the same forms as adjectives add -er / -est||fast||faster||fastest|
with two and more syllable take more / most
|more often||most often|
with -ly take more / most
|carefully||more carefully||most carefully|
Irregular comparative and superlative forms
|much / many / a lot of||more||most|
Some adverbs do not have comparative or superlative forms:
adverbs of time: always, sometimes, never etc.
adverbs of place: here, somewhere etc.
some other adverbs: thus, somehow etc.