1.比較級可分形容詞(adj)的比較和副詞(adv)的比較兩種。
He is taller than I.(他比我高)
He works more diligently than I do.他比我更努力地工作。
2.原級，比較級，最高級的變化
A.規則變化
(a)大部分一個音節和部分兩個音節的形容詞和副詞，字尾+er變成比較級，字尾+est變成最高級
clear clearer clearest
small smaller smallest
narrow narrower narrowest
near nearer nearest
late later latest
(b)字尾是短母音+單子音，加er，est時單子音需再重複一次。
Big bigger biggest
Hot hotter hottest
Fat fatter fattest
(c)字尾是y，前面是輔音，把y變i，再加er,est.
dry drier driest
happy happier happiest
early earlier earliest
三個或三個音節以上及
(d)-able,-ful,-ive,-ing,-less,-ous等字尾的形容詞及末尾是ly的副詞，肯定加more，否定加less變成比較級，肯定加most，否定加least變成最高級。
diligent more diligent most diligent
readable more readable most readable
(less) (least)
beautiful more beautiful most beautiful
(less) (least)
active more active most active
careless more careless most careless
brightly more brightly most brightly
honestly more honestly most honestly
B.不規則變化
good better best
well better best
many(much) more most
late later(較晚的) latest(最晚的) late latter (後者的) last(最後的)
far farther(較遠的) farthest far further(更進一步的) furthest
old older oldest(比較年齡大小) old elder eldest(比較長幼次序)
3.比較級用法
(a)肯定(正面)比較：more…than，-er than～
The house is bright. 這間房子很明亮。
The house is brighter than our old one in New York. 這間房子比我們在紐約的老房子明亮。
The house is the most bright of all the houses in which we have lived. 這間房子是我們所住過最明亮的一間。
(b)否定(反面)比較：less…than～
He is strong. 他很強壯。
He is less strong than Joe. 他沒有喬強壯。
He is the least strong in his class. 他是班上最不強壯的。
(c)同等比較
用於肯定：as+原級+as
用於否定：not as - as或not so - as
An apple is as big as an orange. 蘋果和橘子一樣大。
The cold soup isn't as delicious as the hot one. 冷了的湯沒有熱湯好喝。
I am not so fat as you. 我沒有你那樣胖。