它的用法,有例句哦.
问题描述：
它的用法,有例句哦.
答
once：做副词1.一次,一回.eg：I saw him once and never again.我见过他一回,以后再也没见到过.Once a week ,she wrote to her mother.她一星期一次给她妈妈写信.2：曾经,一度eg：She was oce my best friend.她曾是...