How English Adverbs Form
He works quickly.
The adverb quickly describes the verb work. Quickly here may be replaced by fast. It’s also common to work hard.
He works very quickly.
Very is an adverb describing other adverbs. Here it describes how quickly he works.
He’s a really great worker.
Great is an adjective describing worker. Really describes the adjective great. Really is like very. Great is American for good. So in British the sentence would look like He’s a very good worker.
As with quickly and really, most adverbs are regular as having the –ly suffix added to adjective roots.
She’s a careful driver.
Careful is an adjective describing the noun driver. You can turn many adjectives to adverbs by adding –ly.
She drives carefully.
Let’s paraphrase the sentence with an adverb. Now this adverb carefully describes how she drives. The sentence answers the question How does she drive?
He’s a skilful player.
Skilful is an adjective describing the noun player. You can change it to an adverb with the word-building pattern.
He plays skillfully.
This adverb describes how he plays.