he boy______in the picture is my brother.[ ]

A. on the right                  

B. in the right

C. at the right                  

D. of the right

补体经典途径激活中的C₅转化酶是（）。

A.C3b

B.C4b2b

C.C5aBb

D.C3bnBb

E.C4b2b3b