The crambo Shan in the medieval time includes the four vowels of mandarin language, namely, [an], [ian], [uan]and[yan]. Its changes are very regular in ten counties of the Taihu Area in northern Zhejiang where people speak in Wu dialect. There.are four patterns: 1) the [æ] in Tongxiang and Haining becomes [ε] in other counties, 2) the [ε] there becomes [ø], [ə],
and [ε] in other counties, 3) the [iε] there becomes [iI], [iε], [ie], [i],
and [yə] in other counties, and 4)the iu -class vowel [iε] there becomes [iø], [yə],
, [iI], [i] and [ie] in other counties.