1)a) adverb is a word or a phrase that modifies or qualifies an adj, verb, or other adverb or a word group, expressing a relation of place, time, circumstance, manner, cause, degree, etc... ( e.x: gently, slowly, quietly, carefully, fastly, beautifully, freely, clearly,....)

b) adjective is a word or phrase naming an attribute, added to or grammatically related to a noun to modify or describe it. ( e.x: beautiful, handsome, pretty, cute, slow, fast, noisy,....)
2) so sánh hơn:
short adj: S + to be + adj + er + than + noun/pronoun
long adj: S + to be+ more + adj + than + noun/pronoun
e.x : my brother is taller than you.

so sánh nhất:

short adj: S + to be + the + adj + est + noun/pronoun
long adj: S + to be + the most + adj + noun/pronoun
e.x: my mom is the greatest person in the world.

so sánh bằng:
(+) S + to be/V + as + adj/ adv + as + (S + to be/V) + O
(-) S + to be/V + not + as + adj/adv + as + O
e.x: water is as cold as ice