badly - worse 

conveniently - more conveniently

early - earlier

far - father/ further 

fast - faster

fluently - more fluently

happily - more happily

hard - harder

slowly - more slowly

well - better

late - later 

smartly - more smartly 

responsibly - more responsibly

patiently - more patienly

generously - more generous

cleverly - more cleverly

quickly - more quickly

suitable - more suitable

beautifully - more beautifully

strongly - more strongly 

Công thức chung: adv --> more adv ( vì thường adv rất dài, thường 2 hoặc 3 âm tiết)

Ngoại lệ : fast, well, badly, far, ....