基因型为AaBb的植株,自交后代产生的F1有AAbb、AaBb和aaBB三种基因型,比例为1:2:1,其等位基因在染色体上的位置应是[ ]
A.
B.
C.
D.
答案:D
The second Sunday of May is ______ Mother's Day.
It's ______ special day for children to show their love for their mothers. [ ]
A. a; the
B. the; a
C. 不填; a
D. 不填; the
螨病检查时,病料的采集应在患部采取。