My eyes black.[ ]
A. is
B. are
C. have
答案：B
Tom, I need your help because I don't know ________. [ ]
A. how to do it
B. how to do
C. what to do it
D. what shall I do
个体发育过程中最早合成和分泌的抗体是（）
A.IgG
B.IgM
C.IgA
D.IgD
E.IgE
