比较级的构成规则
1．一般单音节词和少数以-er,-ow结尾的双音节词,比较级在后面加-er,最高级在后面加-est；
（1）单音节词
如：small→smaller→smallest short→shorter→shortest
tall→taller→tallest great→greater→greatest
（2）双音节词
如：clever→cleverer→cleverest narrow→narrower→narrowest
2．以不发音e结尾的单音节词,比较在原级后加-r,最高级在原级后加-st；
如：large→larger→largest nice→nicer→nicest able→abler→ablest
3．在重读闭音节（即：辅音＋元音＋辅音）中,先双写末尾的辅音字母,比较级加-er,最高级加-est；
如：big→bigger→biggest hot→hotter→hottest fat→fatter→fattest
4．以“辅音字母＋y”结尾的双音节词,把y改为i,比较级加-er,最高级加-est；
如：easy→easier→easiest heavy→heavier→heaviest
busy→busier→busiest happy→happier→happiest
5．其他双音节词和多音节词,比较级在前面加more,最高级在前面加most；
如：beautiful→more beautiful→most beautiful
different→more different→most different
easily→more easily→most easily
注意：（1）形容词最高级前通常必须用定冠词 the,副词最高级前可不用.
例句：The Sahara is the biggest desert in the world.
（2） 形容词most前面没有the,不表示最高级的含义,只表示"非常".
It is a most important problem.
=It is a very important problem.
6．有少数形容词、副词的比较级和最高级是不规则的,必须熟记.
如：good→better→best well→better→best
bad→worse→worst ill→worse→worst
old→older/elder→oldest/eldest
many/much→more→most little→less→least
far →further/farther→ furthest/farthest