第23题: [单项选择]A. He finished the negotiation in three days. B. He was on a business trip ten days ago. C. His toughness cost him three more days. D. His business trip lasted thirteen days. 参考答案:D 答案解析:[听力原文] Last month our manager took a ten-day business trip to Chicago, but he had to stay the
第31题: [单项选择]下列哪种乳糖操纵子序列能与RNA聚合酶结台 A. 启动序列 B. O序列 C. CAP结合位点 D. I基因 E. Z基因 参考答案:A 答案解析:原核启动序列或真核启动子是由转录起始点、RNA聚合酶结合位点及控制转录的调节组件组成。启动序列或启动子核苷酸序列会影响其与RNA聚合酶的亲和力,而亲和力大小则直接影响转录起动的频率。在没有乳糖存在时,