prove作"证明是;结果是;事实说明"解时,可用作连系动词.
连系动词解释起来有点复杂,最最常见的连系动词是“is/am/are”,其他连系动词的用法与"be"动词用法类似.
1.一般情况下,句子结构是是谓语+宾语,但是连系动词后面加的不叫宾语,叫表语.连系动词+表语叫做“系表结构”（参考百度百科'连系动词"）
2.常见的连系动词有：be,look,sound,taste,smell,seem,appear,prove,keep,remain,continue,become,get,turn等等（参考百度百科'连系动词"）
3.表语通常是名词,形容词,动词不定式,介词短语或副词,从句来充当.
名词作表语：His efforts,however,proved a failure
形容词作表语：The medicine proved satisfactory.
不定式作表语：Einstein's theory proved to be correct.
介词短语作表语：Perhaps this book will prove of some use to you in your studies.
等等.
详细了解连系动词,请参考语法书中的详细解释,