第2题: [单项选择]{{B}}Passage One
Questions 26 to 29 are based on the passage you have just heard.{{/B}} A. They haven’ t reached a decision yet. B. They have decided to go hunting bears. C. They want to go hunting camping. D. They want to go exploring the country. 参考答案:A 答案解析:[听力原文]26-29
Our family is trying to decide where to go for a vacation this summer. Our son Tom w
第28题: [单项选择]不能通过经典途径激活补体的Ig是(). A. IgM B. IgG3 C. IgA D. IgG1 E. IgE 参考答案:E 答案解析:经典途径是以结合抗原后的IgG或IgM类抗体为主要激活剂,此外非特异性凝集的免疫球蛋白也可以激活,IgE为单体结构,不能通过经典途径激活补体。