[单项选择]关于常见的几种质量控制方法,下列说法错误的是()。 A. 分层法的关键是尽量使同一层内的数据波动大一些,各层间的数据波动小-些 B. 因果分析图是以结果作为特性,以原因作为因素,在它们之间用箭头联系表示因果关系 C. 排列图又称为主次因素分析图或帕雷特(Pareto)图 D. 热处理时淬火温度与工件硬度之间的关系难以用精确的公式或函数关系表示,在这种情况下用相关图来分析就很方便
第21题: [单项选择]{{B}}Questions 29 to 31 are based on the passage you have just heard.{{/B}} A. He was a doctor. B. He was a writer. C. He was an actor. D. He was a teacher. 参考答案:C 答案解析:[听力原文]29-31
Today school children in many countries have high rates of falling eye-sight. Two me