初次免疫应答早期产生的抗体类别主要是（）
A．IgA
B．IgM
C．IgG
D．IgD
E．IgE
参考答案：B
Only when the war was over_____ to go back to the village where he had lived for so many years.
A．was able he
B．he was able
C．able he was
D．was he able
属于网络操作系统的工作模式为（）
