白化病是由隐性致病基因控制的遗传病.一对肤色正常的夫妇生下了一个白化病孩子,那么这对夫妇的基因组成成分是( )
A:HH和Hh
B:HH和hh
C:hh和hh
D:Hh和Hh
- Do you know the boy in blue?
- Yes. I ________ him several times since last month.
不一定在三角形内部的线段是( )
连词成句