题目

基因工程需要专门的工具，其中基因的“剪刀”指（ ）A． DNA连接酶 B． 质粒C． 限制性核酸内切酶 D． 病毒 答案：CWith some snow on top of it,the Yellow Mountain looked fantastic this winter.Actually, I doubt whether we could visit ______mountian in China.A．a most beautifulB．the most beautifulC．a more beautifulD．a beautiful