I really didn’t know who____ for the broken window, for none of them admitted that he had done it.

A．to be blamed

B．is blamed

C．to blame

D．being blamed

抑制膜攻击复合物形成的是（）

A.S蛋白

B.IgM与抗原结合形成的复合物

C.P因子

D.MBL

E.DAF