ABO血型鉴定中，错误的说法是（）

A.用已知特异性抗体检查红细胞上的未知抗原，称为正向定型

B.用已知血型的标准红细胞检查血清中的未知抗体，称为反向定型

C.ABO血型鉴定时，温度应控制在20℃～24℃

D.反向定型试验只需做A型红细胞和B型红细胞检测

E.发生溶血应视为有相应的抗原抗体反应

To have a computer without being connected to the Web is like having an old radio when everybody else has a color TV. That helps explain ______ businesses are setting up Net sites even though profits are nowhere to see.

A．reasons

B．the reason for

C．why

D．why that