题目

 I had worked here ______ you came here. But I shall leave for England ______.    A. before long, before long           B. before long; long before    C. long before, before long           D. long before; long before 答案：C18．下列有关免疫调节的叙述，不正确的是（　　）A．B细胞中具有较多核糖体与其合成和分泌抗体的功能有关B．记忆细胞能够增殖分化为浆细胞，与基因的选择性表达有关C．免疫活性物质不一定有免疫细胞产生D．吞噬细胞对病原体的摄取和处理与膜的流动性有关