我们的老师说，有些双音节形容词在变为比较级和最高级时，有两种方式，既可以后加-er和-est, 也可加 more和most，如 clever:
clever—cleverer—cleverest
clever—more clever—most clever
我想知道能这样变比较级和最高级的双音节形容词都有哪些。谢谢老师！
回答如下：
比较级和最高级的构成，不要他们的变化规则，列如：be+a+比较级+than
比较对象A +系动词+形容词比较级+比较对象B
Nothing is more important than health.
No one is more surprised than I （do)
Tom is taller than any other boy in his class.
Tom is clever than any girl in his class.
比较对象A +行为动词+副词比较级+比较对象B
Tom runs faster than any other boy in his class.
Mary sings more beautifully than any other girl in her class.
比较级和最高级的构成
⑴单音节以及少数双音节的词,在后面直接加–er（比较级）-est（最高级）。
加er，加est的规则如下：
①直接在词尾加- er，-est
tall---taller---tallest
fast---faster---fastest
②以-e结尾的，在后面加-r , -st
large—larger—largest
nice---nicer---nicest
③以辅音字母＋y结尾的词，把y变成i,再加-er , -est
heavy—heavier—heaviest
happy---happier---happiest
[注〕 shy ---- shyer , shyest / shier , shiest
④重读闭音节的词，要双写词尾字母，再加-er , -est
例如：
hot-hotter-hottest
fat-fatter-fattest
wet-wetter-wettest
thin-thinner-thinnest
red-redder-reddest
⑵多音节的词，要在前面加—more. --most
例如：
beautiful----more beautiful---- most beautiful.
important---more important----most important
interesting---more interesting---most interesting
(3)多音节的词，还可以在前面加—less. --least表否定
important---less important---least important
difficult---less difficult----least difficult
（特别备注：少数单音节词前面加 more-, most- 构成比较级和最高级）
tired ---- more tired , most tired
fond ----- more fond , most fond
glad ----- more glad , most glad
bored ---- more bored , most bored
pleased---- more pleased , most pleased
(4)加er/est或者more/most变比较级或者最高级形容词common
common---commoner----commonest
common---more common----most common
clever---cleverer---cleverest
clever-more clever---most clever
gentle---gentler---gentlest
gentle---more gentle---most gentle
polite---politer---politest
polite---more polite---most polite
pleasant---pleasanter---pleasantest
pleasant--more pleasant--most pleasant
Tired---tireder---tiredest
tired---more tired--most tired
The parties to the dispute should be more polite to each other.
争执双方应相互礼貌些.
The more you soften a request, the more polite it becomes.
你愈使请求柔婉, 请求就愈变为客气.
Oil pollution is the commonest cause of death for seabirds.
石油污染是造成海鸟死亡最常见的原因。
Rest assured, he probably has rather more common sense than you realize.
放心吧，他知道的常识很可能比你以为的要多得多。
Cross-dressing is far more common than we realise.
变装现象要远比我们认识到的更加普遍。
Cremation is more common than burial in some countries.
在一些国家,火葬比土葬普遍.
Contractions are much more common in speech than in writing.
缩略词在口语里比在书写中常见得多.
不规则变化
good /well------- better ,best
bad/badly/ill------ worse , worst
many/much-------more , most
little ------ less ------ least
far ---- farther, farthes / further , furthest
old ---- older ----- oldest (GA)
old---- older ----oldest / elder , eldest (GB)
(特别备注1）
下列形容词和副词的比较级和最高级有两种形式）
cruel----- crueler, cruelest
more cruel , most cruel
strict---- stricter , strictest
more strict , most strict
often----- oftener , oftenest
more often , most often
friendly------ friendlier , friendliest
more friendly , most friendly
clever----- cleverer, cleverest
more clever , most clever
(特别备注2）
下列形容词和副词没有比较级和最高（即表示”最高程度”或”绝对状态”的形容词和副词没有比较级和最高级）
empty , wrong , perfect , unique , extreme , excellent , favourite favorite , true , right , correct , extremely .