In autumn the days _____________ shorter and shorter. The leaves _____________ yellow. A . get; turn B . get; turns C . got; turn D . have got; have turned 答案:A 某影院有60排座位,每排70个座号,一次报告会坐满了听众,会后留下座号为15的所有听众60人进行座谈,这是运用了
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A.抽签法 B.随机数法 C.系统抽样法 D.分层抽样法