题目

Researchers at the University of Kansas say that people can accurately judge 90 percent of a stranger's personality simply by looking at the person's shoes. “Shoes convey useful information about their wearers”, the authors wrote in the new study published in the Journal of Research in Personality．     Lead researcher Omri Gillath said the judgments were based on the style, cost, color and condition of someone's shoes. In the study, 63 University of Kansas researchers looked at pictures showing 208 different pairs of shoes worn by the study's participants. Volunteers in the st 阅读下面文段，按要求回答问题： 植物农药又称生物农药，是利用有毒植物的多种杀虫成分，经过提炼后生产的农药，由于它们的杀虫有效成分为天然物质，因而施用后较易分解为无毒物质，对环境无污染。 下列对“植物农药”概述正确的是： A．它是提炼有毒植物中的无毒物质生成的 B．它是利用多种有毒物质的杀虫成分，经过提炼生成 C．它是提炼有毒植物中多种对杀虫有效的天然物质制造的 D．它是利用有毒物质中使害虫不能产生免疫力的杀虫成分，然后经过提炼而成