题目

完形填空 阅读下面短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处的最佳选项。On 28 of March Richard Byrd stood outside the small house. He shook hands with the men who were leaving. They were heading back to the main camp on the coast of Antarctica (南极洲). He would  1   to work at the base camp.“I don't like leaving you here alone,Pete Demas said.I’ll be  2  ,Byrd replied. He was looking forward to the challenge of spending the winter at the base camp. He would be recording the weather. There was plenty of food and fuel 一个基因型为AaBb的精原细胞，产生的4个精子若出现了以下情况．下列对相应情况的分析正确的是（　　）精子的种类及数量比对相应情况的分析AAB：ab=2：2这两对等位基因必定位于一对同源染色体上BAB：Ab：aB：ab=1：1：1：1这两对等位基因必定位于两对同源染色体上CAaB：b=2：2一定发生了染色体结构变异DAB：aB：ab=1：1：2有一个A基因突变成了a A、AB、BC、CD、D