big-bigger-biggest
hot-hotter-hottest
wet-wetter-wettest
fat-fatter-fattest
thin-thinner--thinnest
red-redder-reddest
sad-sadder-saddest
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；
（1）单音节词
如：small→smaller short→shorter；tall→taller great→greater
（2）双音节词
如：clever→cleverer narrow→narrower
2．以不发音e结尾的单音节词,比较在原级后加-r；
如：large→larger nice→nicer able→abler
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；
如：big→bigger hot→hotter fat→fatter
4．以“辅音字母＋y”结尾的双音节词,把y改为i,比较级加-er；
如：easy→easier heavy→heavier；busy→busier happy→happier
5．其他双音节词和多音节词,比较级在前面加more；
如：beautiful→more beautiful；different→more different；easily→more easily
