GRE Reading Comprehension: PPO-GRE阅读PPO - E6T663M6TS85YLGMS

Last year, Fillmore County's farmers used Sordane, a highly effective nonpersistent pesticide, on their crops. Though crop yields were satisfactory, aerial spraying of Sordane increased the county's incidence of respiratory illness. This year, farmers sprayed with the weaker pesticide Kaskanine instead. Crop yields were unchanged, while the county experienced a significant decline in respiratory illness. Therefore, if farmers use only Kaskanine next year, the reduced incidence of respiratory illness will be maintained without sacrificing crop yields.