题目

. —May I speak to Professor Brown, please? —Sorry, he isn’t in. This is his assistant speaking. Can I help you?. —______.     A. Oh, you can          B. Oh, it’s a pity C. I hope to see him soon    D. I should think so 答案：D 解析: 略 把成年三倍体鲫鱼的肾脏细胞核移植到二倍体的去核卵细胞里，培养并获得了克隆鱼。该克隆鱼 [　　] A． 是二倍体 B． 是有性生殖的产物 C． 高度不育 D． 性状与二倍体鲫鱼完全相同