计算:
(b-2a)2-4a(a-b)。
解:原式=b2-4ab+4a2-4a2+4ab=b2
某种遗传病受一对等位基因控制,下图为该遗传病的系谱图。下列叙述正确的是:
A.该病为常染色体隐性遗传病,Ⅲ2为杂合子
B.该病为伴X染色体显性遗传病,Ⅱ4为纯合子
C.该病为伴X染色体隐性遗传病,Ⅱ1为纯合子
D.该病为常染色体显性遗传病,Ⅱ3为纯合子
- Who has done that again?
-_______ you ask? Little Tom, of course!
A.Must
B.Can
C.Would
D.Need