第21题: [单项选择]The economic recession has meant that job ______ is a rare thing. A. security B. safety C. protection D. secureness 参考答案:A 答案解析:[考点] 考查名词词义辨析。 A、B两项均有“安全”之意,但是A指抽象事物,而B用来指具体的概念。根据句意,这里说的是“就业保障”,指的是抽象概念,故选A。C项protection意为“保护
A. were more exact than sound waves B. could not be detected C. could penetrate fog and clouds D. were easier to use than sound waves 参考答案:C 答案解析:[参考译文] 英国人运用无线电波因为它们可以穿透云雾。 [试题分析] 本题考查对细节的理解。 [详细解答] 从文章第二段第二句我们知道,他们(英国人)使用无线电波而不是声波是因为无线电波能