38．A 细节理解题。由第二段最后一句“Farmers could then spotspray, using 50 to 70 percent less pesticide than they otherwise would(采取点喷，农民们可以节省平时用量的50%至70%的杀虫剂)”可知。
39．C 细节理解题。由第三段的第一句“The bad news is that Paley's company closed down in 1984，after only three years.Farmers resisted the new technology and longterm backers were hard to find.”可知，红外线扫描技术应用于农业遇到了一些问题，原因有两个：一是农民对新技术的抵制；二是难以找到长期的赞助商。还有一处明显的提示出现在文章的最后一句“But only if Paley finds the financial backing which he failed to obtain 10 years ago”，从该句提供的信息同样可以反推出10年前的情形。
