OG13-68 A选项 求翻译
whether there are insect pests that sometimes reduce feed-corn yields,but against which commonly used insecticides and the genetic modification are equally ineffective。
主要是but 后面,有点凌乱
against which commonly used insecticides and the genetic modification are equally ineffective是定语从句,which指代insect pests,against表示针对这些害虫,还原这句定语从句是:commonly used insecticides and the genetic modification are equally ineffective against the insect pests.