单项选择题
A.C4a B.C3b C.C5b D.C2b E.C2a
A.IgG与抗原结合成的免疫复合物 B.IgM C.IgG2 D.聚合的IgA E.SIgA
A.C3 B.C8 C.C1q D.C5 E.C4