为什么well begun,half done,而不是well begin,half done?

well begun is half done. Well begun is half done well begun is half done的begin用法问题 Well begun,half done.begun的用法 well begun is half done英语作文 翻译谚语：Well begun is half done. 翻译：Well begun is half done. Well begun is half done!为什么用副词而不是形容词good呢? Well begun is half done.well begun是名词性质吗?不然为什么做主语? Well begin is half done 啥意思? Well begun is half done.其中begun的词性. Well began ,half done.