Avouch, which is no longer in common use, means guarantee, solemnly aver, prove by assertion, maintain the truth or existence of, vouch for .... Avow means own publicly to, make no secret of, not shrink from admitting, acknowledge one's responsibility for .... Vouch is now common only in the phrase vouch for, which has taken the place of avouch in ordinary use, & means pledge one's word for .... [Fowler]
Avouch,現已不常用,意爲保證,莊嚴地斷言,通過斷言證明,維護真相或存在,爲...作證.... Avow 意爲公開擁有,不隱瞞,不迴避承認,承認自己的責任.... Vouch 現在只在短語 vouch for 中常見,已經取代了 avouch 在普通用法中,意爲保證....[福勒]