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【单选题】
在一个种群中随机抽出一定数量的个体，其中基因型为aa的个体占18%，基因型为Aa的个体占78%，基因型为AA的个体占4%。则基因A和基因a的频率分别是 [ ]A.
82%和18%
B.
43%和57%
C.
36%和64%
D.
92%和8%
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皮皮学刷刷变学霸
举一反三
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【单选题】促红细胞生成素(EPO)基因能在大肠杆菌中表达，但却不能用大肠杆菌工程菌生产人促红细胞生成素，这是因为( )。
A.
人EPO对大肠杆菌有毒性作用
B.
人EPO在大肠杆菌中不稳定
C.
大肠杆菌内毒素与人EPO特异性结合并使其灭活
D.
人EPO对大肠杆菌蛋白水解酶极为敏感
E.
大肠杆菌不能使人EPO糖基化
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A.
People think highly of advertising.
B.
People criticize advertising.
C.
Some people welcome advertising while others don't.
D.
There are more criticisms of advertising than praises.
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A.
saying hello to them whenever you meet them
B.
accepting and understanding their different cultures
C.
sharing happiness and hardship with them
D.
helping them get what they hope for
【多选题】促红细胞生成素是( )。
A.
通过特异受体作用于红系集落形成单位
B.
它是红系集落形成单位生存和增殖的必需条件
C.
它主要产生于肾髓质
D.
肝也能产生一部分
E.
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A.
kept as it is for a long time
B.
not fixed
C.
easy to improve
D.
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A.
where students can extend their y of a major
B.
where students can learn a practical skill
C.
where only the rich students can go for study
D.
whose admission standard is low
相关题目：
【多选题】促红细胞生成素是( )。
A.
通过特异受体作用于红系集落形成单位
B.
它是红系集落形成单位生存和增殖的必需条件
C.
它主要产生于肾髓质
D.
肝也能产生一部分
E.
它是一种酸性糖蛋白