mindmap root((作证)) certify usually applies to a written statement, especially one carrying a signature or seal: ~ied that the candidate had met all the requirements. attest applies to oral or written testimony usually from experts or witnesses and often under oath or by word of honor: ~ed the authenticity of the document. witness applies to the subscribing of one's own name as evidence of the genuineness of a document: two persons who ~ed the signing of the will. vouch suggests that the one who testifies is a competent authority or a reliable person who will stand behind an affirmation: willing to ~ for the woman's integrity.