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
