将杂合子个体逐代自交3次，在F3代中纯合子的比例为（）
A.1/8
B.7/8
C.7/16
D.9/16
参考答案：B
Only when I read this story for a second time to appreciate its beauty.
A．had I began
B．that I began
C．I began
D．did I begin
凝聚的作用机理是什么？
