【简答题】听材料,回答问题。 1. Why did the mother lock the door with three locks every night? [ ] A. Because the door was not strong enough. B. Because her daughter asked her to do so. C. Because she thought a thie...
【简答题】一根 2 m 长的填充柱的操作条件及流出曲线的数据如下: 流量 20 mL / min ( 50 °C) 柱温 50 °C 柱前压力: 133.32 kpa 柱后压力 101.32kPa 空气保留时间 0.50 min 正庚烷保留时间 4.10 min 若正庚烷的半峰宽为 0.25 min ,用正庚烷计算色谱柱的理论塔板数和理论塔板高度;