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【单选题】
绵羊的白色由显性基因(R)控制，黑色由隐性基因(r)控制。现有一只白色公羊与一只白色母羊交配，生了一只黑色小羊。那只公羊和母羊的基因组成分别是
[ ]
A.
Rr、Rr
B.
RR、RR
C.
RR、rr
D.
Rr、RR
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