与Ⅱ型超敏反应发生无关的是（）
A.补体
B.巨噬细胞
C.肥大细胞
D.IgG
E.IgM
参考答案：C
He has a friend who ____ the piano very well .
A．play
B．playing
C．plays
D．played
渠道冲突
