A. A student and a professor. B. A physicist and a biologist. C. Two students. D. Two professors. 参考答案:C 答案解析:[听力原文]8-10 W: Oh, am I glad to see you! You took Introduction to Science, didn't you M: I sur
第15题:[单选题]CD4 分子主要表达在哪种细胞上 A. 辅助性 T 细胞(Th) B. 细胞毒 T 细胞(CTL 或 Tc) C. NK 细胞 D. B 细胞 E. 中性粒细胞 参考答案:A