题型分类:否定事实信息题
原文定位:整个段落都在讨论这个内容,可直接通过选项定位。
选项分析:
B 选项,introduction of new crop 未提及。
A 选项,对应第三句,... increasing research was devoted to improving seeds, developing chemical fertilizers, and advancing livestock。
C 选项,对应最后一句,It also included mechanical cream separators and other food-processing devices that improved supply。
D 选项,对应倒数第三句,After 1861, with the development of land-grant universities in the United States that had huge agricultural programs, American crop-production research added to this mix。
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