同等学力英语辅导by在句子中的成分分析

　　by是一个基本词汇。意思是靠近，通过，作副词时表示经过，在旁边;作介词时表示在……之前。常用形态的有prep.和adv.形式。那么by在以下句子中做什么成分?如何理解?下面新阳光教育辅导老师为大家讲解一下：

　　The overall result has been to make entrance to professional geological journals harder for amateurs ,a result that has been reinforced by the widespread introduction of refereeing ，first by national journals in the nineteenth century and then by several local geological journals in the twentieth century.

　　这里的三个by,都是用在被动语态中引出动作的发出者的。

　　这句话的主句为：The overall result has been to make entrance to professional geological journals harder for amateurs 。后面的：a result that has been reinforced by the widespread introduction of refereeing ，first by national journals in the nineteenth century and then by several local geological journals in the twentieth century中，

　　1. by the widespread introduction of refereeing

　　2.by national journals in the nineteenth century

　　3.by several local geological journals in the twentieth century.是三个对等的成分，by后面的内容都是reinforce这个动作的执行者。

　　以上题目如有同学还不清楚，欢迎咨询老师获取帮助，新阳光教育预祝同学们顺利通过考试。