红细胞血型中较为复杂的遗传多态性血型系统是（）
A.ABO血型系统
B.Rh血型系统
C.MN血型系统
D.Kell血型系统
E.P血型系统
参考答案：B
His disabled legs _______ him to a wheelchair all his life.
A．condemned
B．fastened
C．applied
D．cast
劳动时间的增加与产量增加成正比。
