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【单选题】
现有一只白色公羊与一只白色母羊交配，产下一只罴色小羊。若羊毛的白色由显性基因(R)控制，黑色由隐性基因(r)控制，则这只黑色小羊的基因组成是（）
A.
Rr
B.
RR
C.
rr
D.
Rr或RR
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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Passage Two In 1997, devotees of home electronics eagerly awaited the DVD player, a new device that could play movies without videotape, and with greater clarity. It caught on even faste...
A.
die economic realities of its practicality
B.
robust economic growth
C.
economic problems of hi-tech companies
D.
ignorance of the technology