Adjectives tell us something about a noun or pronoun.
Adjectives do not have a plural form. We use the same form for singular nouns (warm day), plural nouns (warm days, NOT warms days) and mass nouns (warm weather).
Many words are only adjectives, but sometimes we can make adjectives from
the -ing form of a verb: swimming pool
a past participle: tired boys
a noun: football stadium
Adverbs give extra information. They can tell us when (Lesson 71), how often (Lesson 73), how (Lesson 80) and where (for example, Lesson 79). They can also make a description stronger or weaker (Lesson 67).
ADJECTIVE: bad, careful, slow, probable, happy
ADVERB: badly, carefully, slowly, probably, happily
He is a hard worker.
He is a fast worker.
It's an early train.
She was late.
He works hard.
He works fast.
It arrives early.
She arrived late.
He is a good worker.
He works well.