1. 一般情况下直接在词尾加er 或est:

tall—taller–tallest stong—stronger—stongest

2. 以不发音的字母e结尾的单词在词尾加r 或st:

nice—nicer—nicest late—later—latest

3.以辅音字母加y结尾的单词,变y为i,加er或est:

dry—drier—driest easy—easier—easiest

4.以重读闭音节结尾的词,末尾只有一个辅音字母时，双写这个辅音字母再加er或est：

fat—fatter—fattest big—bigger—biggest