Qt1:(quy tắc tổng quát 1)
Cheap:........ cheaper - cheapest
Short:................shorter - shortest

Small:............. smaller - smallest
Qt2:
Fine:................... finer - finest 
Safe:................... safer - safest
Large - larger - largest
Qt3:(quy tắc tổng quát 2)
Beautiful/beautifully:..... more beautiful/ more beautifully
Qt4:
Hot:..... hotter - hottest
Big:..... bigger - biggest
Fit:...... fitter - fittest
Sad:....... sadder - saddest
Thin:.......... thinner - thinnest
Qt5:(đc coi là tính từ ngắn)
Happy:..... happier - happiest
Early:...... earlier - earliest
Busy:........ busier - busiest
Dirty:........ dirtier - durtiest
Easy:........... easier - easiest
Funny:........ funnier - funniest
Heavy :........ heavier - heaviest
Friendly:......... friendlier - friendliest
Lucky:........... luckier - luckiest
Pretty:...........prettier - prettiest
Silly:....….... sillier - 
Qt6:(vừa đc coi là ngắn/dài)
Quiet:......... quiteter - 
Shallow:........... shallower - shallowest
Simple:........ simpler - simplest
Clever:........... cleverer - cleverest
Common:.......... commoner - commonest
Cruel:.........crueler - cruelest
Gentle:......... gentler - gentlest
Pleasant:...........pleasanter - pleasanter
Polite:....... politer - politest
Stupid:......... stupider - stupidest