Since 1980, productivity improvements in manufacturing have moved the United States from a position of acute decline in manufacturing to one of world prominence. Manufacturing,
从句意来看,DE没有used一词是不合理的,C选项除掉定语强调的是Employing the same techniques,researchers have been able to increase xxx
DE选项是:(这里的to不能省略,造成了句意上转基因植物和potatoes是一类的感觉)Employing the same techniques to genetically enhance plants,researchers have been able to increase xxx
从语法来看,E选项的that跳跃修饰容易引起歧义,D选项有主谓一致问题。
总结,做题目抓语义要从宏观角度,不要抓住C的细节,像到底是不是so that表目的的语义。
possible ... may (redundancy)