9351请在第__（49）__处填上正确答案。 查看材料A.This allowed sc3876

请在第__（49）__处填上正确答案。 查看材料 A.This allowed scientists to gauge the pace and progress of the ecological recovery. B.Yet in other businesses，such as farming and property development，ant surveys aren"tused widely. C.Employing those people are expensive. D.They do this by sorting the ants，counting their numbers and comparing the results withthose of earlier surveys. E.The evolution of ant species may have a strong impact on our ecosystem. F.Others will die out for lack of food. 请帮忙给出正确答案和分析，谢谢！